title: how do i solve an error caused by flutter phone_state package
body: <p>pubspec.yaml file.</p>
  <p><code>dependencies: flutter: sdk: flutter flutter_phone_state: ^0.5.9 cupertino_icons: ^1.0.2</code></p>
  <p>main.dart file</p>
  <pre><code>`import 'package:flutter_phone_state/flutter_phone_state.dart';`
  </code></pre>
  <p>the error:</p>
  <p>Launching lib\main.dart on sdk gphone x86 in debug mode...
  Running Gradle task 'assembleDebug'...
  Error: Cannot run with sound null safety, because the following dependencies
  don't support null safety:</p>
  <ul>
  <li>package:flutter_phone_state</li>
  <li>package:logging</li>
  <li>package:url_launcher</li>
  <li>package:uuid</li>
  <li>package:url_launcher_platform_interface</li>
  <li>package:crypto</li>
  <li>package:convert</li>
  <li>package:plugin_platform_interface</li>
  </ul>
  <p>For solutions, see <a href="https://dart.dev/go/unsound-null-safety" rel="nofollow noreferrer">https://dart.dev/go/unsound-null-safety</a></p>
  <p>FAILURE: Build failed with an exception.</p>
  <ul>
  <li><p>Where:
  Script 'C:\src\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 1035</p>
  </li>
  <li><p>What went wrong:
  Execution failed for task ':app:compileFlutterBuildDebug'.</p>
  </li>
  </ul>
  <blockquote>
  <p>Process 'command 'C:\src\flutter\bin\flutter.bat'' finished with non-zero exit value 1</p>
  </blockquote>
  <ul>
  <li><p>Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.</p>
  </li>
  <li><p>Get more help at <a href="https://help.gradle.org" rel="nofollow noreferrer">https://help.gradle.org</a></p>
  </li>
  </ul>
  <p>BUILD FAILED in 13s
  Exception: Gradle task assembleDebug failed with exit code 1</p>