<h2 dir="auto">Steps to Reproduce</h2>
<p dir="auto">Please tell us what you were doing and what went wrong. If you are running flutter tools from the command line, please try adding the <code class="notranslate">-v</code> or <code class="notranslate">--verbose</code> option to gather more information.</p>
<blockquote>
<p dir="auto">I created a new flutter project. Then I went to the flutter inspector and clicked on "Toggle Platform Mode".</p>
</blockquote>
<p dir="auto">If the problem is with your application's rendering, please attach a screenshot and any relevant source code.<br>
If you are getting an exception in the logs, and your code is implicated in the first few frames, then please include the source code for the functions involved.</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/7094734/38721747-9be5e024-3efb-11e8-9e30-1d6367c3cf3f.png"><img src="https://user-images.githubusercontent.com/7094734/38721747-9be5e024-3efb-11e8-9e30-1d6367c3cf3f.png" alt="screen shot 2018-04-13 at 09 18 03" style="max-width: 100%;"></a></p>
<h2 dir="auto">Logs</h2>
<p dir="auto">Run your application with <code class="notranslate">flutter run</code> and attach all the log output.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Launching lib/main.dart on iPhone X in debug mode...
Syncing files to device iPhone X...
Switched platform rendering to Android.
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown building SlideTransition(animation: AnimationController#cf714(⏭
1.000; paused; for MaterialPageRoute&lt;dynamic&gt;(/))➩ProxyAnimation➩Cubic(0.40, 0.00, 0.20,
1.00)➩Tween&lt;Offset&gt;(Offset(0.0, 0.3) → Offset(0.0, 0.0))➩Offset(0.0, 0.0), state:
_AnimatedState#162a1):
'package:flutter/src/rendering/object.dart': Failed assertion: line 1792 pos 12: '() {
final AbstractNode parent = this.parent;
if (parent is RenderObject)
return parent._needsCompositing;
return true;
}()': is not true.

Either the assertion indicates an error in the framework itself, or we should provide substantially
more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new
"><pre class="notranslate"><code class="notranslate">Launching lib/main.dart on iPhone X in debug mode...
Syncing files to device iPhone X...
Switched platform rendering to Android.
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown building SlideTransition(animation: AnimationController#cf714(⏭
1.000; paused; for MaterialPageRoute&lt;dynamic&gt;(/))➩ProxyAnimation➩Cubic(0.40, 0.00, 0.20,
1.00)➩Tween&lt;Offset&gt;(Offset(0.0, 0.3) → Offset(0.0, 0.0))➩Offset(0.0, 0.0), state:
_AnimatedState#162a1):
'package:flutter/src/rendering/object.dart': Failed assertion: line 1792 pos 12: '() {
final AbstractNode parent = this.parent;
if (parent is RenderObject)
return parent._needsCompositing;
return true;
}()': is not true.

Either the assertion indicates an error in the framework itself, or we should provide substantially
more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new

</code></pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="When the exception was thrown, this was the stack:
#2      RenderObject.markNeedsCompositingBitsUpdate (package:flutter/src/rendering/object.dart)
#3      RenderObject.attach (package:flutter/src/rendering/object.dart:1232:7)
#4      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.attach (package:flutter/src/rendering/object.dart:2588:11)
#5      AbstractNode.adoptChild (package:flutter/src/foundation/node.dart:128:13)
#6      RenderObject.adoptChild (package:flutter/src/rendering/object.dart:1077:11)
#7      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.child= (package:flutter/src/rendering/object.dart:2583:7)
#8      SingleChildRenderObjectElement.insertChildRenderObject (package:flutter/src/widgets/framework.dart:4652:18)
#9      RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:4496:35)
#10     Element._activateWithParent (package:flutter/src/widgets/framework.dart:2957:5)
#11     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2882:18)
#12     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#13     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4637:14)
#14     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#15     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#16     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4637:14)
#17     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#18     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#19     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4637:14)
#20     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#21     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#22     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#23     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#24     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#25     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3752:11)
#26     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#27     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#28     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#30     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#31     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#32     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#33     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#34     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#35     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#36     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#37     StatefulElement.update (package:flutter/src/widgets/framework.dart:3782:5)
#38     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#39     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4644:14)
#40     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#41     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#42     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#43     ProxyElement.update (package:flutter/src/widgets/framework.dart:3892:5)
#44     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#45     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4644:14)
#46     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#47     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#48     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#49     StatefulElement.update (package:flutter/src/widgets/framework.dart:3782:5)
#50     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#51     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#52     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#53     StatelessElement.update (package:flutter/src/widgets/framework.dart:3685:5)
#54     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#55     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4644:14)
#56     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#57     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#58     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#59     ProxyElement.update (package:flutter/src/widgets/framework.dart:3892:5)
#60     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#61     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#62     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#63     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2225:33)
#64     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:621:20)
#65     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
#66     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
#67     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
#68     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.scheduleWarmUpFrame.&lt;anonymous closure&gt; (package:flutter/src/scheduler/binding.dart:751:7)
#70     _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
#71     _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
#72     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:165:12)
(elided 3 frames from class _AssertionError and package dart:async)"><pre class="notranslate"><code class="notranslate">When the exception was thrown, this was the stack:
#2      RenderObject.markNeedsCompositingBitsUpdate (package:flutter/src/rendering/object.dart)
#3      RenderObject.attach (package:flutter/src/rendering/object.dart:1232:7)
#4      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.attach (package:flutter/src/rendering/object.dart:2588:11)
#5      AbstractNode.adoptChild (package:flutter/src/foundation/node.dart:128:13)
#6      RenderObject.adoptChild (package:flutter/src/rendering/object.dart:1077:11)
#7      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.child= (package:flutter/src/rendering/object.dart:2583:7)
#8      SingleChildRenderObjectElement.insertChildRenderObject (package:flutter/src/widgets/framework.dart:4652:18)
#9      RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:4496:35)
#10     Element._activateWithParent (package:flutter/src/widgets/framework.dart:2957:5)
#11     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2882:18)
#12     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#13     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4637:14)
#14     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#15     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#16     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4637:14)
#17     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#18     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#19     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4637:14)
#20     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#21     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#22     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#23     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#24     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#25     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3752:11)
#26     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#27     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#28     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#30     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#31     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3605:5)
#32     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3600:5)
#33     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2890:14)
#34     Element.updateChild (package:flutter/src/widgets/framework.dart:2693:12)
#35     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#36     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#37     StatefulElement.update (package:flutter/src/widgets/framework.dart:3782:5)
#38     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#39     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4644:14)
#40     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#41     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#42     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#43     ProxyElement.update (package:flutter/src/widgets/framework.dart:3892:5)
#44     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#45     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4644:14)
#46     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#47     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#48     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#49     StatefulElement.update (package:flutter/src/widgets/framework.dart:3782:5)
#50     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#51     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#52     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#53     StatelessElement.update (package:flutter/src/widgets/framework.dart:3685:5)
#54     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#55     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4644:14)
#56     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#57     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#58     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#59     ProxyElement.update (package:flutter/src/widgets/framework.dart:3892:5)
#60     Element.updateChild (package:flutter/src/widgets/framework.dart:2682:15)
#61     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3636:16)
#62     Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
#63     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2225:33)
#64     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:621:20)
#65     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
#66     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
#67     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
#68     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.scheduleWarmUpFrame.&lt;anonymous closure&gt; (package:flutter/src/scheduler/binding.dart:751:7)
#70     _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
#71     _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
#72     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:165:12)
(elided 3 frames from class _AssertionError and package dart:async)
</code></pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="════════════════════════════════════════════════════════════════════════════════════════════════════
Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 102 pos 12: '_owner != null': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1091 pos 12: 'child.parentData != null': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1091 pos 12: 'child.parentData != null': is not true.
Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 102 pos 12: '_owner != null': is not true.
Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 102 pos 12: '_owner != null': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1091 pos 12: 'child.parentData != null': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3480 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3480 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1457 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1457 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1457 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
Another exception was thrown: Tried to paint a RenderObject before its compositing bits were updated.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 3099 pos 12: '_ancestorChain.length == 1': is not true.
Switched platform rendering to iOS."><pre class="notranslate"><code class="notranslate">════════════════════════════════════════════════════════════════════════════════════════════════════
Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 102 pos 12: '_owner != null': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1091 pos 12: 'child.parentData != null': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1091 pos 12: 'child.parentData != null': is not true.
Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 102 pos 12: '_owner != null': is not true.
Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 102 pos 12: '_owner != null': is not true.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1091 pos 12: 'child.parentData != null': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3480 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3480 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1457 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1457 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1457 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
Another exception was thrown: Tried to paint a RenderObject before its compositing bits were updated.
Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 3099 pos 12: '_ancestorChain.length == 1': is not true.
Switched platform rendering to iOS.
</code></pre></div>
<p dir="auto">Run <code class="notranslate">flutter analyze</code> and attach any output of that command also.</p>
<h2 dir="auto">Flutter Doctor</h2>
<p dir="auto">Paste the output of running <code class="notranslate">flutter doctor -v</code> here.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="[✓] Flutter (Channel beta, v0.2.8, on Mac OS X 10.13.4 17E199, locale en-ZA)
    • Flutter version 0.2.8 at /Users/WingHinChan/Documents/FlutterSDK/flutter
    • Framework revision b397406561 (10 days ago), 2018-04-02 13:53:20 -0700
    • Engine revision c903c217a1
    • Dart version 2.0.0-dev.43.0.flutter-52afcba357

[✓] Android toolchain - develop for Android devices (Android SDK 27.0.3)
    • Android SDK at /Users/WingHinChan/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-27, build-tools 27.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b01)
    • All Android licenses accepted.

[✓] iOS toolchain - develop for iOS devices (Xcode 9.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 9.3, Build version 9E145
    • ios-deploy 1.9.2
    • CocoaPods version 1.5.0

[✓] Android Studio (version 3.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b01)

[!] IntelliJ IDEA Community Edition (version 2016.1.1)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • For information about installing plugins, see
      https://flutter.io/intellij-setup/#installing-the-plugins
    ✗ This install is older than the minimum recommended version of 2017.1.0.

[✓] Connected devices (1 available)
    • iPhone X • FE19AC9F-A4B4-4AE7-9D06-9DD21DDFEBAE • ios • iOS 11.3 (simulator)

! Doctor found issues in 1 category."><pre class="notranslate"><code class="notranslate">[✓] Flutter (Channel beta, v0.2.8, on Mac OS X 10.13.4 17E199, locale en-ZA)
    • Flutter version 0.2.8 at /Users/WingHinChan/Documents/FlutterSDK/flutter
    • Framework revision b397406561 (10 days ago), 2018-04-02 13:53:20 -0700
    • Engine revision c903c217a1
    • Dart version 2.0.0-dev.43.0.flutter-52afcba357

[✓] Android toolchain - develop for Android devices (Android SDK 27.0.3)
    • Android SDK at /Users/WingHinChan/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-27, build-tools 27.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b01)
    • All Android licenses accepted.

[✓] iOS toolchain - develop for iOS devices (Xcode 9.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 9.3, Build version 9E145
    • ios-deploy 1.9.2
    • CocoaPods version 1.5.0

[✓] Android Studio (version 3.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b01)

[!] IntelliJ IDEA Community Edition (version 2016.1.1)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • For information about installing plugins, see
      https://flutter.io/intellij-setup/#installing-the-plugins
    ✗ This install is older than the minimum recommended version of 2017.1.0.

[✓] Connected devices (1 available)
    • iPhone X • FE19AC9F-A4B4-4AE7-9D06-9DD21DDFEBAE • ios • iOS 11.3 (simulator)

! Doctor found issues in 1 category.
</code></pre></div>
<blockquote>
<p dir="auto">For more information about diagnosing and reporting Flutter bugs, please see <a href="https://flutter.io/bug-reports/" rel="nofollow">https://flutter.io/bug-reports/</a>.</p>
</blockquote>
<p dir="auto">I am able to trigger a reproducible assertion when adding (or removing) a <code class="notranslate">padding</code> argument to a <code class="notranslate">Container</code> and doing a hot-reload.  Note that the assertion happens only during a hot-reload, not during a hot-restart nor when doing the initial <code class="notranslate">flutter run</code>.</p>
<p dir="auto">I've tried to distill the reproduction case to be as small as possible.  Note that the use of a <code class="notranslate">GlobalKey</code>, a <code class="notranslate">GridView</code>, and the <code class="notranslate">BoxConstraints</code> all seem to be relevant.</p>
<h2 dir="auto">The failure</h2>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ flutter run
Using hardware rendering with device Android SDK built for x86. If you get graphics artifacts, consider enabling software rendering with &quot;--enable-software-rendering&quot;.
Launching lib/main.dart on Android SDK built for x86 in debug mode...
Initializing gradle...                                           0.7s
Resolving dependencies...                                        1.8s
Gradle task 'assembleDebug'...                                   3.8s
Built build/app/outputs/apk/debug/app-debug.apk.
Installing build/app/outputs/apk/app.apk...                      0.8s
Syncing files to device Android SDK built for x86...
D/        (16785): HostConnection::get() New Host Connection established 0xde8a9fc0, tid 16811
D/EGL_emulation(16785): eglMakeCurrent: 0xe1205ca0: ver 2 0 (tinfo 0xcd0cf9e0)
 2.5s

🔥  To hot reload changes while running, press &quot;r&quot;. To hot restart (and rebuild state), press &quot;R&quot;.
An Observatory debugger and profiler on Android SDK built for x86 is available at: http://127.0.0.1:46673/
For a more detailed help message, press &quot;h&quot;. To detach, press &quot;d&quot;; to quit, press &quot;q&quot;.

Initializing hot reload...                                      I/flutter (16785): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (16785): The following assertion was thrown building Container(constraints: BoxConstraints(0.0&lt;=w&lt;=Infinity,
I/flutter (16785): h=200.0)):
I/flutter (16785): 'package:flutter/src/rendering/object.dart': Failed assertion: line 1854 pos 12: '() {
I/flutter (16785):       final AbstractNode parent = this.parent;
I/flutter (16785):       if (parent is RenderObject)
I/flutter (16785):         return parent._needsCompositing;
I/flutter (16785):       return true;
I/flutter (16785):     }()': is not true.
I/flutter (16785):
I/flutter (16785): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (16785): more information in this error message to help you determine and fix the underlying cause.
I/flutter (16785): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (16785):   https://github.com/flutter/flutter/issues/new
I/flutter (16785):
I/flutter (16785): When the exception was thrown, this was the stack:
I/flutter (16785): #2      RenderObject.markNeedsCompositingBitsUpdate (package:flutter/src/rendering/object.dart:1854:12)
I/flutter (16785): #3      RenderObject.attach (package:flutter/src/rendering/object.dart:1294:7)
I/flutter (16785): #4      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.attach (package:flutter/src/rendering/object.dart:2720:11)
I/flutter (16785): #5      AbstractNode.adoptChild (package:flutter/src/foundation/node.dart:132:13)
I/flutter (16785): #6      RenderObject.adoptChild (package:flutter/src/rendering/object.dart:1139:11)
I/flutter (16785): #7      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.child= (package:flutter/src/rendering/object.dart:2715:7)
I/flutter (16785): #8      SingleChildRenderObjectElement.insertChildRenderObject (package:flutter/src/widgets/framework.dart:4815:18)
I/flutter (16785): #9      RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:4659:35)
I/flutter (16785): #10     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #11     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #12     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #13     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #14     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #15     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #16     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #17     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #18     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #19     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #20     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #21     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #22     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #23     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #24     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #25     Element._activateWithParent (package:flutter/src/widgets/framework.dart:3003:5)
I/flutter (16785): #26     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2928:18)
I/flutter (16785): #27     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #28     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4800:14)
I/flutter (16785): #29     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2936:14)
I/flutter (16785): #30     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #31     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #32     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #33     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3662:5)
I/flutter (16785): #34     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3657:5)
I/flutter (16785): #35     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2936:14)
I/flutter (16785): #36     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #37     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4800:14)
I/flutter (16785): #38     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2936:14)
I/flutter (16785): #39     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #40     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #41     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #42     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #43     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #44     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #45     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #46     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #47     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #48     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #49     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #50     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #51     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #52     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #53     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #54     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #55     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #56     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #57     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #58     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #59     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #60     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #61     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #62     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #63     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #64     StatefulElement.update (package:flutter/src/widgets/framework.dart:3839:5)
I/flutter (16785): #65     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #66     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #67     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #68     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #69     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #70     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #71     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #72     StatefulElement.update (package:flutter/src/widgets/framework.dart:3839:5)
I/flutter (16785): #73     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #74     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #75     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #76     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #77     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #78     ProxyElement.update (package:flutter/src/widgets/framework.dart:3951:5)
I/flutter (16785): #79     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #80     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #81     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #82     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #83     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #84     StatefulElement.update (package:flutter/src/widgets/framework.dart:3839:5)
I/flutter (16785): #85     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #86     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #87     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #88     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #89     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #90     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #91     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #92     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #93     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #94     ProxyElement.update (package:flutter/src/widgets/framework.dart:3951:5)
I/flutter (16785): #95     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #96     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #97     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #98     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2272:33)
I/flutter (16785): #99     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;SemanticsBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:673:20)
I/flutter (16785): #100    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;SemanticsBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)
I/flutter (16785): #101    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter (16785): #102    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter (16785): #103    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.scheduleWarmUpFrame.&lt;anonymous closure&gt; (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter (16785): #105    _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (16785): #106    _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (16785): #107    _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (16785): (elided 3 frames from class _AssertionError and package dart:async)
I/flutter (16785): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3532 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.

Reloaded 1 of 416 libraries in 674ms.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3532 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
I/flutter (16785): Another exception was thrown: NoSuchMethodError: The method '_enableMutationsToDirtySubtrees' was called on null.
I/flutter (16785): Another exception was thrown: NoSuchMethodError: The setter 'offset=' was called on null.
I/flutter (16785): Another exception was thrown: RenderBox was not laid out: RenderPadding#3ac5e NEEDS-PAINT DETACHED
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1493 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
I/chatty  (16785): uid=10080(com.example.visibilitydetectorsample) Thread-2 identical 2 lines
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1493 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
I/flutter (16785): Another exception was thrown: NoSuchMethodError: The getter 'offset' was called on null.

Application finished."><pre class="notranslate"><code class="notranslate">$ flutter run
Using hardware rendering with device Android SDK built for x86. If you get graphics artifacts, consider enabling software rendering with "--enable-software-rendering".
Launching lib/main.dart on Android SDK built for x86 in debug mode...
Initializing gradle...                                           0.7s
Resolving dependencies...                                        1.8s
Gradle task 'assembleDebug'...                                   3.8s
Built build/app/outputs/apk/debug/app-debug.apk.
Installing build/app/outputs/apk/app.apk...                      0.8s
Syncing files to device Android SDK built for x86...
D/        (16785): HostConnection::get() New Host Connection established 0xde8a9fc0, tid 16811
D/EGL_emulation(16785): eglMakeCurrent: 0xe1205ca0: ver 2 0 (tinfo 0xcd0cf9e0)
 2.5s

🔥  To hot reload changes while running, press "r". To hot restart (and rebuild state), press "R".
An Observatory debugger and profiler on Android SDK built for x86 is available at: http://127.0.0.1:46673/
For a more detailed help message, press "h". To detach, press "d"; to quit, press "q".

Initializing hot reload...                                      I/flutter (16785): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (16785): The following assertion was thrown building Container(constraints: BoxConstraints(0.0&lt;=w&lt;=Infinity,
I/flutter (16785): h=200.0)):
I/flutter (16785): 'package:flutter/src/rendering/object.dart': Failed assertion: line 1854 pos 12: '() {
I/flutter (16785):       final AbstractNode parent = this.parent;
I/flutter (16785):       if (parent is RenderObject)
I/flutter (16785):         return parent._needsCompositing;
I/flutter (16785):       return true;
I/flutter (16785):     }()': is not true.
I/flutter (16785):
I/flutter (16785): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (16785): more information in this error message to help you determine and fix the underlying cause.
I/flutter (16785): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (16785):   https://github.com/flutter/flutter/issues/new
I/flutter (16785):
I/flutter (16785): When the exception was thrown, this was the stack:
I/flutter (16785): #2      RenderObject.markNeedsCompositingBitsUpdate (package:flutter/src/rendering/object.dart:1854:12)
I/flutter (16785): #3      RenderObject.attach (package:flutter/src/rendering/object.dart:1294:7)
I/flutter (16785): #4      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.attach (package:flutter/src/rendering/object.dart:2720:11)
I/flutter (16785): #5      AbstractNode.adoptChild (package:flutter/src/foundation/node.dart:132:13)
I/flutter (16785): #6      RenderObject.adoptChild (package:flutter/src/rendering/object.dart:1139:11)
I/flutter (16785): #7      _RenderProxyBox&amp;RenderBox&amp;RenderObjectWithChildMixin.child= (package:flutter/src/rendering/object.dart:2715:7)
I/flutter (16785): #8      SingleChildRenderObjectElement.insertChildRenderObject (package:flutter/src/widgets/framework.dart:4815:18)
I/flutter (16785): #9      RenderObjectElement.attachRenderObject (package:flutter/src/widgets/framework.dart:4659:35)
I/flutter (16785): #10     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #11     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #12     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #13     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #14     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #15     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #16     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #17     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #18     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #19     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #20     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #21     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #22     Element.attachRenderObject.&lt;anonymous closure&gt; (package:flutter/src/widgets/framework.dart:2856:13)
I/flutter (16785): #23     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3716:14)
I/flutter (16785): #24     Element.attachRenderObject (package:flutter/src/widgets/framework.dart:2855:5)
I/flutter (16785): #25     Element._activateWithParent (package:flutter/src/widgets/framework.dart:3003:5)
I/flutter (16785): #26     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2928:18)
I/flutter (16785): #27     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #28     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4800:14)
I/flutter (16785): #29     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2936:14)
I/flutter (16785): #30     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #31     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #32     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #33     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3662:5)
I/flutter (16785): #34     ComponentElement.mount (package:flutter/src/widgets/framework.dart:3657:5)
I/flutter (16785): #35     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2936:14)
I/flutter (16785): #36     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #37     SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4800:14)
I/flutter (16785): #38     Element.inflateWidget (package:flutter/src/widgets/framework.dart:2936:14)
I/flutter (16785): #39     Element.updateChild (package:flutter/src/widgets/framework.dart:2739:12)
I/flutter (16785): #40     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #41     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #42     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #43     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #44     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #45     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #46     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #47     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #48     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #49     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #50     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #51     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #52     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #53     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #54     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #55     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #56     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #57     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #58     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #59     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #60     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #61     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #62     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #63     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #64     StatefulElement.update (package:flutter/src/widgets/framework.dart:3839:5)
I/flutter (16785): #65     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #66     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #67     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #68     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #69     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #70     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #71     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #72     StatefulElement.update (package:flutter/src/widgets/framework.dart:3839:5)
I/flutter (16785): #73     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #74     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #75     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #76     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #77     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #78     ProxyElement.update (package:flutter/src/widgets/framework.dart:3951:5)
I/flutter (16785): #79     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #80     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #81     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #82     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #83     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #84     StatefulElement.update (package:flutter/src/widgets/framework.dart:3839:5)
I/flutter (16785): #85     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #86     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #87     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #88     StatelessElement.update (package:flutter/src/widgets/framework.dart:3742:5)
I/flutter (16785): #89     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #90     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4807:14)
I/flutter (16785): #91     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #92     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #93     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #94     ProxyElement.update (package:flutter/src/widgets/framework.dart:3951:5)
I/flutter (16785): #95     Element.updateChild (package:flutter/src/widgets/framework.dart:2728:15)
I/flutter (16785): #96     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3693:16)
I/flutter (16785): #97     Element.rebuild (package:flutter/src/widgets/framework.dart:3530:5)
I/flutter (16785): #98     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2272:33)
I/flutter (16785): #99     _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;SemanticsBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:673:20)
I/flutter (16785): #100    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;SemanticsBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)
I/flutter (16785): #101    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter (16785): #102    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter (16785): #103    _WidgetsFlutterBinding&amp;BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.scheduleWarmUpFrame.&lt;anonymous closure&gt; (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter (16785): #105    _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (16785): #106    _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (16785): #107    _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (16785): (elided 3 frames from class _AssertionError and package dart:async)
I/flutter (16785): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/foundation/node.dart': Failed assertion: line 106 pos 12: '_owner != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1153 pos 12: 'child.parentData != null': is not true.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3532 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.

Reloaded 1 of 416 libraries in 674ms.
I/flutter (16785): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3532 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
I/flutter (16785): Another exception was thrown: NoSuchMethodError: The method '_enableMutationsToDirtySubtrees' was called on null.
I/flutter (16785): Another exception was thrown: NoSuchMethodError: The setter 'offset=' was called on null.
I/flutter (16785): Another exception was thrown: RenderBox was not laid out: RenderPadding#3ac5e NEEDS-PAINT DETACHED
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1493 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
I/chatty  (16785): uid=10080(com.example.visibilitydetectorsample) Thread-2 identical 2 lines
I/flutter (16785): Another exception was thrown: 'package:flutter/src/rendering/box.dart': Failed assertion: line 1493 pos 18: 'debugDoingThisResize || debugDoingThisLayout ||
I/flutter (16785): Another exception was thrown: NoSuchMethodError: The getter 'offset' was called on null.

Application finished.
</code></pre></div>
<h2 dir="auto">The code</h2>
<div class="highlight highlight-source-dart notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="import 'package:flutter/material.dart';

void main() {
  return runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      // XXX: Removing (or adding) the following line and doing a hot-reload
      //      triggers a framework assertion.  Hot restart is fine.
      padding: const EdgeInsets.all(5),
      child: Container(
        constraints: const BoxConstraints(minHeight: 200, maxHeight: 200),
        child: GridView.count(
          key: _myKey,
          crossAxisCount: 2,
          children: &lt;Widget&gt;[Placeholder(), Placeholder()],
        ),
      ),
    );
  }
}

final _myKey = LabeledGlobalKey('MyKey');"><pre class="notranslate"><span class="pl-k">import</span> <span class="pl-s">'package:flutter/material.dart'</span>;

<span class="pl-k">void</span> <span class="pl-en">main</span>() {
  <span class="pl-k">return</span> <span class="pl-en">runApp</span>(<span class="pl-c1">MyApp</span>());
}

<span class="pl-k">class</span> <span class="pl-c1">MyApp</span> <span class="pl-k">extends</span> <span class="pl-c1">StatelessWidget</span> {
  <span class="pl-k">@override</span>
  <span class="pl-c1">Widget</span> <span class="pl-en">build</span>(<span class="pl-c1">BuildContext</span> context) {
    <span class="pl-k">return</span> <span class="pl-c1">MaterialApp</span>(
      home<span class="pl-k">:</span> <span class="pl-c1">MyHomePage</span>(),
    );
  }
}

<span class="pl-k">class</span> <span class="pl-c1">MyHomePage</span> <span class="pl-k">extends</span> <span class="pl-c1">StatelessWidget</span> {
  <span class="pl-c1">MyHomePage</span>({<span class="pl-c1">Key</span> key}) <span class="pl-k">:</span> <span class="pl-c1">super</span>(key<span class="pl-k">:</span> key);

  <span class="pl-k">@override</span>
  <span class="pl-c1">Widget</span> <span class="pl-en">build</span>(<span class="pl-c1">BuildContext</span> context) {
    <span class="pl-k">return</span> <span class="pl-c1">Container</span>(
      <span class="pl-c">// XXX: Removing (or adding) the following line and doing a hot-reload</span>
      <span class="pl-c">//      triggers a framework assertion.  Hot restart is fine.</span>
      padding<span class="pl-k">:</span> <span class="pl-k">const</span> <span class="pl-c1">EdgeInsets</span>.<span class="pl-en">all</span>(<span class="pl-c1">5</span>),
      child<span class="pl-k">:</span> <span class="pl-c1">Container</span>(
        constraints<span class="pl-k">:</span> <span class="pl-k">const</span> <span class="pl-c1">BoxConstraints</span>(minHeight<span class="pl-k">:</span> <span class="pl-c1">200</span>, maxHeight<span class="pl-k">:</span> <span class="pl-c1">200</span>),
        child<span class="pl-k">:</span> <span class="pl-c1">GridView</span>.<span class="pl-en">count</span>(
          key<span class="pl-k">:</span> _myKey,
          crossAxisCount<span class="pl-k">:</span> <span class="pl-c1">2</span>,
          children<span class="pl-k">:</span> <span class="pl-k">&lt;</span><span class="pl-c1">Widget</span><span class="pl-k">&gt;</span>[<span class="pl-c1">Placeholder</span>(), <span class="pl-c1">Placeholder</span>()],
        ),
      ),
    );
  }
}

<span class="pl-k">final</span> _myKey <span class="pl-k">=</span> <span class="pl-c1">LabeledGlobalKey</span>(<span class="pl-s">'MyKey'</span>);</pre></div>
<h2 dir="auto">Doctor</h2>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ flutter doctor -v

[✓] Flutter (Channel unknown, v0.10.2-pre.81, on Linux, locale en_US.UTF-8)
    • Flutter version 0.10.2-pre.81 at /home/jamesdlin/git/flutter/flutter
    • Framework revision 26131d917a (2 weeks ago), 2018-10-23 17:36:25 -0700
    • Engine revision 3236b49cea
    • Dart version 2.1.0 (build 2.1.0-dev.8.0 bf26f760b1)

[✓] Android toolchain - develop for Android devices (Android SDK 28.0.3)
    • Android SDK at /home/jamesdlin/Android/Sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: /home/jamesdlin/android-studio/jre/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)
    • All Android licenses accepted.

[✓] Android Studio (version 3.2)
    • Android Studio at /home/jamesdlin/android-studio
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)

[✓] VS Code (version 1.28.1)
    • VS Code at /usr/share/code
    • Flutter extension version 2.19.0

[✓] Connected device (1 available)
    • Android SDK built for x86 • emulator-5554 • android-x86 • Android 8.1.0 (API 27) (emulator)

• No issues found!"><pre class="notranslate"><code class="notranslate">$ flutter doctor -v

[✓] Flutter (Channel unknown, v0.10.2-pre.81, on Linux, locale en_US.UTF-8)
    • Flutter version 0.10.2-pre.81 at /home/jamesdlin/git/flutter/flutter
    • Framework revision 26131d917a (2 weeks ago), 2018-10-23 17:36:25 -0700
    • Engine revision 3236b49cea
    • Dart version 2.1.0 (build 2.1.0-dev.8.0 bf26f760b1)

[✓] Android toolchain - develop for Android devices (Android SDK 28.0.3)
    • Android SDK at /home/jamesdlin/Android/Sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: /home/jamesdlin/android-studio/jre/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)
    • All Android licenses accepted.

[✓] Android Studio (version 3.2)
    • Android Studio at /home/jamesdlin/android-studio
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1136-b06)

[✓] VS Code (version 1.28.1)
    • VS Code at /usr/share/code
    • Flutter extension version 2.19.0

[✓] Connected device (1 available)
    • Android SDK built for x86 • emulator-5554 • android-x86 • Android 8.1.0 (API 27) (emulator)

• No issues found!
</code></pre></div>