flutter - 成功迁移到空安全后，Flutter 项目未运行

Question

成功迁移到空安全后，我在运行颤振项目时遇到问题。我使用安卓工作室。这是颤振医生的结果：

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 2.2.1, on Microsoft Windows [Version 10.0.19041.985], locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
[√] Chrome - develop for the web
[√] Android Studio (version 4.1.0)
[√] Connected device (3 available)

• No issues found!

这是过时的依赖检查的结果：

See https://dart.dev/go/null-safety-migration for a migration guide.

Analyzing project...
[-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\]
All sources appear to be already migrated.  Nothing to do.

但是，我收到由依赖项引起的错误（未直接在我的 pubspec.yaml 中使用，但似乎其中一个包正在使用它，并且此依赖项没有更新空安全性）。因此，当我尝试从 android studio 运行它时，我得到以下输出（即使 dart migrate 甚至应该提到内部包依赖项，因为它可能会阻止运行）：

Launching lib\main.dart on Android SDK built for x86 in debug mode...
Running Gradle task 'assembleDebug'...
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:tinycolor

For solutions, see https://dart.dev/go/unsound-null-safety
lib/screens/invitations_screen.dart:115:5: Warning: Operand of null-aware operation '?.' has type 'TabController' which excludes null.
 - 'TabController' is from 'package:flutter/src/material/tab_controller.dart' ('/D:/Flutter/flutterV1.0.0.0/packages/flutter/lib/src/material/tab_controller.dart').
    _c1?.dispose();
    ^
/D:/Flutter/flutterV1.0.0.0/.pub-cache/hosted/pub.dartlang.org/flutter_datetime_picker-1.5.1/lib/flutter_datetime_picker.dart:311:32: Warning: Operand of null-aware operation '??' has type 'Color' which excludes null.
 - 'Color' is from 'dart:ui'.
                  color: theme.backgroundColor ?? Colors.white,
                               ^


FAILURE: Build failed with an exception.

* Where:
Script 'D:\Flutter\flutterV1.0.0.0\packages\flutter_tools\gradle\flutter.gradle' line: 1035

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'D:\Flutter\flutterV1.0.0.0\bin\flutter.bat'' finished with non-zero exit value 1

* 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.

* Get more help at https://help.gradle.org

BUILD FAILED in 23s
Exception: Gradle task assembleDebug failed with exit code 1

所以我最终尝试在没有 sound-null-safety 的情况下运行，但仍然出现错误（我尝试了 flutter clean --> Invalidate Caches/Restart --> pub get --> flutter run --no-sound-null-safety但仍然是同样的问题）：

Using hardware rendering with device Android SDK built for x86. If you notice graphics artifacts, consider enabling software rendering with "--enable-software-rendering".
Launching lib\main.dart on Android SDK built for x86 in debug mode...
Running Gradle task 'assembleDebug'...
Running Gradle task 'assembleDebug'... Done                        22.1s
√  Built build\app\outputs\flutter-apk\app-debug.apk.
Error connecting to the service protocol: failed to connect to http://127.0.0.1:57596/NxvUCmZt3sM=/

注意：在重新启动android studio的最后一次尝试之前，这个最后一个错误也在“错误连接...”语句之前显示了一个异常，我记得这个异常（抱歉没有完整的堆栈跟踪，因为它没有'不再显示）：

androidx WindowInsetsCompat ---> Preconditions.checkNonNull 上的 NullPointerException

编辑 在按照@Taur的建议在一个新的项目中完成依赖项之后，事实证明，在没有声音-null-safety的情况下运行时的问题是由flutter_typeahead依赖项引起的，在我运行项目时抛出了前面提到的异常：

E/AndroidRuntime(11173): java.lang.ExceptionInInitializerError
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat.<clinit>(WindowInsetsCompat.java:82)
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat.toWindowInsetsCompat(WindowInsetsCompat.java:169)
E/AndroidRuntime(11173):    at androidx.core.view.ViewCompat$Api21Impl$1.onApplyWindowInsets(ViewCompat.java:4753)
E/AndroidRuntime(11173):    at android.view.View.dispatchApplyWindowInsets(View.java:9799)
E/AndroidRuntime(11173):    at android.view.ViewGroup.dispatchApplyWindowInsets(ViewGroup.java:7076)
E/AndroidRuntime(11173):    at android.view.ViewGroup.dispatchApplyWindowInsets(ViewGroup.java:7080)
E/AndroidRuntime(11173):    at android.view.ViewGroup.dispatchApplyWindowInsets(ViewGroup.java:7080)
E/AndroidRuntime(11173):    at android.view.ViewRootImpl.dispatchApplyInsets(ViewRootImpl.java:1632)
E/AndroidRuntime(11173):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1734)
E/AndroidRuntime(11173):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1443)
E/AndroidRuntime(11173):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7125)
E/AndroidRuntime(11173):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:935)
E/AndroidRuntime(11173):    at android.view.Choreographer.doCallbacks(Choreographer.java:747)
E/AndroidRuntime(11173):    at android.view.Choreographer.doFrame(Choreographer.java:682)
E/AndroidRuntime(11173):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:921)
E/AndroidRuntime(11173):    at android.os.Handler.handleCallback(Handler.java:873)
E/AndroidRuntime(11173):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(11173):    at android.os.Looper.loop(Looper.java:164)
E/AndroidRuntime(11173):    at android.app.ActivityThread.main(ActivityThread.java:6649)
E/AndroidRuntime(11173):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(11173):    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
E/AndroidRuntime(11173):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:826)
E/AndroidRuntime(11173): Caused by: java.lang.NullPointerException
E/AndroidRuntime(11173):    at androidx.core.util.Preconditions.checkNotNull(Preconditions.java:119)
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat.toWindowInsetsCompat(WindowInsetsCompat.java:169)
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat.toWindowInsetsCompat(WindowInsetsCompat.java:149)
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat$BuilderImpl20.build(WindowInsetsCompat.java:1706)
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat$Builder.build(WindowInsetsCompat.java:1588)
E/AndroidRuntime(11173):    at androidx.core.view.WindowInsetsCompat$Impl.<clinit>(WindowInsetsCompat.java:748)
E/AndroidRuntime(11173):    ... 22 more 

标签： flutterdart-null-safety