<h2 dir="auto">Steps to Reproduce</h2>
<p dir="auto">Just messing around with the basic template, but since you asked for a report, here you go. :)</p>
<p dir="auto">The assertion occurred when I added <code class="notranslate">[100]</code> to <code class="notranslate">Colors.teal</code>:</p>
<p dir="auto"><em>main.dart</em></p>
<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() =&gt; runApp(new MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Demo',
      theme: new ThemeData(
        primarySwatch: Colors.teal[100],
      ),
      home: new MyHomePage(title: 'Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() =&gt; new _MyHomePageState();
}

class _MyHomePageState extends State&lt;MyHomePage&gt; {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new Center(
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: &lt;Widget&gt;[
            new Text(
              'You have pushed the blue button ',
            ),
            new Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
            new Text(
              _counter == 1 ? 'time' : 'times'
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'încrement',
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}"><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">=&gt;</span> <span class="pl-en">runApp</span>(<span class="pl-k">new</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-c">// This widget is the root of your application.</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-k">new</span> <span class="pl-c1">MaterialApp</span>(
      title<span class="pl-k">:</span> <span class="pl-s">'Demo'</span>,
      theme<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">ThemeData</span>(
        primarySwatch<span class="pl-k">:</span> <span class="pl-c1">Colors</span>.teal[<span class="pl-c1">100</span>],
      ),
      home<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">MyHomePage</span>(title<span class="pl-k">:</span> <span class="pl-s">'Demo Home Page'</span>),
    );
  }
}

<span class="pl-k">class</span> <span class="pl-c1">MyHomePage</span> <span class="pl-k">extends</span> <span class="pl-c1">StatefulWidget</span> {
  <span class="pl-c1">MyHomePage</span>({<span class="pl-c1">Key</span> key, <span class="pl-c1">this</span>.title}) <span class="pl-k">:</span> <span class="pl-c1">super</span>(key<span class="pl-k">:</span> key);
  <span class="pl-k">final</span> <span class="pl-c1">String</span> title;

  <span class="pl-k">@override</span>
  <span class="pl-c1">_MyHomePageState</span> <span class="pl-en">createState</span>() <span class="pl-k">=&gt;</span> <span class="pl-k">new</span> <span class="pl-c1">_MyHomePageState</span>();
}

<span class="pl-k">class</span> <span class="pl-c1">_MyHomePageState</span> <span class="pl-k">extends</span> <span class="pl-c1">State</span>&lt;<span class="pl-c1">MyHomePage</span>&gt; {
  <span class="pl-c1">int</span> _counter <span class="pl-k">=</span> <span class="pl-c1">0</span>;

  <span class="pl-k">void</span> <span class="pl-en">_incrementCounter</span>() {
    <span class="pl-en">setState</span>(() {
      _counter<span class="pl-k">++</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-k">new</span> <span class="pl-c1">Scaffold</span>(
      appBar<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">AppBar</span>(
        title<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Text</span>(widget.title),
      ),
      body<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Center</span>(
        child<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Column</span>(
          mainAxisAlignment<span class="pl-k">:</span> <span class="pl-c1">MainAxisAlignment</span>.center,
          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-k">new</span> <span class="pl-c1">Text</span>(
              <span class="pl-s">'You have pushed the blue button '</span>,
            ),
            <span class="pl-k">new</span> <span class="pl-c1">Text</span>(
              <span class="pl-s">'$<span class="pl-v">_counter</span>'</span>,
              style<span class="pl-k">:</span> <span class="pl-c1">Theme</span>.<span class="pl-en">of</span>(context).textTheme.display1,
            ),
            <span class="pl-k">new</span> <span class="pl-c1">Text</span>(
              _counter <span class="pl-k">==</span> <span class="pl-c1">1</span> <span class="pl-k">?</span> <span class="pl-s">'time'</span> <span class="pl-k">:</span> <span class="pl-s">'times'</span>
            ),
          ],
        ),
      ),
      floatingActionButton<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">FloatingActionButton</span>(
        onPressed<span class="pl-k">:</span> _incrementCounter,
        tooltip<span class="pl-k">:</span> <span class="pl-s">'încrement'</span>,
        child<span class="pl-k">:</span> <span class="pl-k">new</span> <span class="pl-c1">Icon</span>(<span class="pl-c1">Icons</span>.add),
      ), <span class="pl-c">// This trailing comma makes auto-formatting nicer for build methods.</span>
    );
  }
}</pre></div>
<h2 dir="auto">Logs</h2>
<p dir="auto"><em>DEBUG CONSOLE output</em></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&gt; Launching lib/main.dart on Chris's 7+ in debug mode...
&gt; Signing iOS app for device deployment using developer identity: &quot;iPhone Developer: noah HURWITZ (L236D3NJ9F)&quot;
&gt; Xcode build done
&gt; Reloaded 466 of 482 libraries in 2,277ms.
&gt; 
&gt; _counter++
&gt; global evaluation not supported
&gt; [VERBOSE-1:FlutterAppDelegate.mm(77)]
&gt; Reloaded 1 of 482 libraries in 790ms.
&gt; Reloaded 1 of 482 libraries in 1,922ms.
&gt; Reloaded 1 of 482 libraries in 710ms.
&gt; Reloaded 1 of 482 libraries in 750ms.
&gt; Reloaded 1 of 482 libraries in 872ms.
&gt; Reloaded 1 of 482 libraries in 746ms.
&gt; ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
&gt; The following assertion was thrown building MyApp(dirty):
&gt; type 'Color' is not a subtype of type 'MaterialColor' of 'primarySwatch' where
&gt; Color is from dart:ui
&gt; MaterialColor is from package:flutter/src/material/colors.dart
&gt; int is from dart:core
&gt; Either the assertion indicates an error in the framework itself, or we should provide substantially
&gt; more information in this error message to help you determine and fix the underlying cause.
&gt; In either case, please report this assertion by filing a bug on GitHub:
&gt; https://github.com/flutter/flutter/issues/new
&gt; When the exception was thrown, this was the stack:
&gt; #0      new ThemeData (package:flutter/src/material/theme_data.dart:78:19)
&gt; #1      MyApp.build (/private/var/mobile/Containers/Data/Application/D21E0705-8433-45E8-8459-EAA541373594/tmp/fluttertestSMPzry/fluttertest/lib/main.dart:11:18)
&gt; #2      StatelessElement.build (package:flutter/src/widgets/framework.dart:3678:28)
&gt; #3      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3625:15)
&gt; #4      Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
&gt; #5      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2225:33)
&gt; #6      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:621:20)
&gt; #7      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
&gt; #8      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
&gt; #9      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
&gt; #10     BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.scheduleWarmUpFrame.&lt;anonymous closure&gt; (package:flutter/src/scheduler/binding.dart:751:7)
&gt; #12     _Timer._runTimers (dart:isolate-patch/dart:isolate/timer_impl.dart:382)
&gt; #13     _Timer._handleMessage (dart:isolate-patch/dart:isolate/timer_impl.dart:416)
&gt; #14     _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:165)
&gt; (elided one frame from package dart:async-patch)
&gt; ════════════════════════════════════════════════════════════════════════════════════════════════════
&gt; Reloaded 1 of 482 libraries in 913ms."><pre class="notranslate"><code class="notranslate">&gt; Launching lib/main.dart on Chris's 7+ in debug mode...
&gt; Signing iOS app for device deployment using developer identity: "iPhone Developer: noah HURWITZ (L236D3NJ9F)"
&gt; Xcode build done
&gt; Reloaded 466 of 482 libraries in 2,277ms.
&gt; 
&gt; _counter++
&gt; global evaluation not supported
&gt; [VERBOSE-1:FlutterAppDelegate.mm(77)]
&gt; Reloaded 1 of 482 libraries in 790ms.
&gt; Reloaded 1 of 482 libraries in 1,922ms.
&gt; Reloaded 1 of 482 libraries in 710ms.
&gt; Reloaded 1 of 482 libraries in 750ms.
&gt; Reloaded 1 of 482 libraries in 872ms.
&gt; Reloaded 1 of 482 libraries in 746ms.
&gt; ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
&gt; The following assertion was thrown building MyApp(dirty):
&gt; type 'Color' is not a subtype of type 'MaterialColor' of 'primarySwatch' where
&gt; Color is from dart:ui
&gt; MaterialColor is from package:flutter/src/material/colors.dart
&gt; int is from dart:core
&gt; Either the assertion indicates an error in the framework itself, or we should provide substantially
&gt; more information in this error message to help you determine and fix the underlying cause.
&gt; In either case, please report this assertion by filing a bug on GitHub:
&gt; https://github.com/flutter/flutter/issues/new
&gt; When the exception was thrown, this was the stack:
&gt; #0      new ThemeData (package:flutter/src/material/theme_data.dart:78:19)
&gt; #1      MyApp.build (/private/var/mobile/Containers/Data/Application/D21E0705-8433-45E8-8459-EAA541373594/tmp/fluttertestSMPzry/fluttertest/lib/main.dart:11:18)
&gt; #2      StatelessElement.build (package:flutter/src/widgets/framework.dart:3678:28)
&gt; #3      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3625:15)
&gt; #4      Element.rebuild (package:flutter/src/widgets/framework.dart:3478:5)
&gt; #5      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2225:33)
&gt; #6      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding&amp;WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:621:20)
&gt; #7      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding&amp;PaintingBinding&amp;RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:208:5)
&gt; #8      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
&gt; #9      BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
&gt; #10     BindingBase&amp;GestureBinding&amp;ServicesBinding&amp;SchedulerBinding.scheduleWarmUpFrame.&lt;anonymous closure&gt; (package:flutter/src/scheduler/binding.dart:751:7)
&gt; #12     _Timer._runTimers (dart:isolate-patch/dart:isolate/timer_impl.dart:382)
&gt; #13     _Timer._handleMessage (dart:isolate-patch/dart:isolate/timer_impl.dart:416)
&gt; #14     _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:165)
&gt; (elided one frame from package dart:async-patch)
&gt; ════════════════════════════════════════════════════════════════════════════════════════════════════
&gt; Reloaded 1 of 482 libraries in 913ms.
</code></pre></div>
<p dir="auto"><em>flutter analyze</em></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&gt; Analyzing /Users/clozach/Documents/fluttertest...
&gt; No issues found!
&gt; Ran in 5.9s"><pre class="notranslate"><code class="notranslate">&gt; Analyzing /Users/clozach/Documents/fluttertest...
&gt; No issues found!
&gt; Ran in 5.9s
</code></pre></div>
<h2 dir="auto">Flutter Doctor</h2>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&gt; [✓] Flutter (Channel beta, v0.1.5, on Mac OS X 10.12.6 16G1212, locale en-US)
&gt;     • Flutter version 0.1.5 at /Users/clozach/Documents/flutter
&gt;     • Framework revision 3ea4d06340 (3 weeks ago), 2018-02-22 11:12:39 -0800
&gt;     • Engine revision ead227f118
&gt;     • Dart version 2.0.0-dev.28.0.flutter-0b4f01f759
&gt; 
&gt; [✓] Android toolchain - develop for Android devices (Android SDK 25.0.3)
&gt;     • Android SDK at /Users/clozach/Library/Android/sdk
&gt;     • Android NDK at /Users/clozach/Library/Android/sdk/ndk-bundle
&gt;     • Platform android-25, build-tools 25.0.3
&gt;     • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
&gt;     • Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)
&gt; 
&gt; [✓] iOS toolchain - develop for iOS devices (Xcode 9.2)
&gt;     • Xcode at /Applications/Xcode.app/Contents/Developer
&gt;     • Xcode 9.2, Build version 9C40b
&gt;     • ios-deploy 1.9.2
&gt;     • CocoaPods version 1.4.0
&gt; 
&gt; [✓] Android Studio (version 2.3)
&gt;     • Android Studio at /Applications/Android Studio.app/Contents
&gt;     • Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)
&gt; 
&gt; [✓] VS Code (version 1.21.1)
&gt;     • VS Code at /Users/clozach/Applications/Visual Studio Code.app/Contents
&gt;     • Dart Code extension version 2.10.0
&gt; 
&gt; [✓] Connected devices (2 available)
&gt;     • Chris's 7+ • 70ac7560f7462ec1c00624e5caea54391427c752 • ios • iOS 11.2.5
&gt;     • iPhone X   • CB912A56-5869-4312-9977-E00B6B7BF326     • ios • iOS 11.2 (simulator)
&gt; 
&gt; • No issues found!"><pre class="notranslate"><code class="notranslate">&gt; [✓] Flutter (Channel beta, v0.1.5, on Mac OS X 10.12.6 16G1212, locale en-US)
&gt;     • Flutter version 0.1.5 at /Users/clozach/Documents/flutter
&gt;     • Framework revision 3ea4d06340 (3 weeks ago), 2018-02-22 11:12:39 -0800
&gt;     • Engine revision ead227f118
&gt;     • Dart version 2.0.0-dev.28.0.flutter-0b4f01f759
&gt; 
&gt; [✓] Android toolchain - develop for Android devices (Android SDK 25.0.3)
&gt;     • Android SDK at /Users/clozach/Library/Android/sdk
&gt;     • Android NDK at /Users/clozach/Library/Android/sdk/ndk-bundle
&gt;     • Platform android-25, build-tools 25.0.3
&gt;     • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
&gt;     • Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)
&gt; 
&gt; [✓] iOS toolchain - develop for iOS devices (Xcode 9.2)
&gt;     • Xcode at /Applications/Xcode.app/Contents/Developer
&gt;     • Xcode 9.2, Build version 9C40b
&gt;     • ios-deploy 1.9.2
&gt;     • CocoaPods version 1.4.0
&gt; 
&gt; [✓] Android Studio (version 2.3)
&gt;     • Android Studio at /Applications/Android Studio.app/Contents
&gt;     • Java version OpenJDK Runtime Environment (build 1.8.0_112-release-b06)
&gt; 
&gt; [✓] VS Code (version 1.21.1)
&gt;     • VS Code at /Users/clozach/Applications/Visual Studio Code.app/Contents
&gt;     • Dart Code extension version 2.10.0
&gt; 
&gt; [✓] Connected devices (2 available)
&gt;     • Chris's 7+ • 70ac7560f7462ec1c00624e5caea54391427c752 • ios • iOS 11.2.5
&gt;     • iPhone X   • CB912A56-5869-4312-9977-E00B6B7BF326     • ios • iOS 11.2 (simulator)
&gt; 
&gt; • No issues found!
</code></pre></div>
<p dir="auto">We should hide the message saying this could be a framework bug if the first stack frame is not in the framework. In fact we should probably figure out which package is to blame and then explicitly name that.</p>
<p dir="auto">Depends on <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="155609978" data-permission-text="Title is private" data-url="https://github.com/flutter/flutter/issues/4021" data-hovercard-type="issue" data-hovercard-url="/flutter/flutter/issues/4021/hovercard" href="https://github.com/flutter/flutter/issues/4021">#4021</a>.</p>