Flutter：警告：空感知操作“！”的操作数 具有排除 null 的类型“WidgetsBinding”

Question

最近，我的调试控制台显示了以前未显示的内容。当我使用包时会发生这种情况flutter_typeahead。我不知道这是错误还是警告。下面是我的调试控制台：

Launching lib\main.dart on Chrome in debug mode...
: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Documents/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.removeObserver(this);
                   ^

: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Documents/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addObserver(this);
                   ^
: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Documents/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addPostFrameCallback((duration) {
                   ^
: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Documents/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.removeObserver(this);
                   ^

: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Documents/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addObserver(this);
                   ^

: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../Documents/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addPostFrameCallback((duration) {
                   ^
This app is linked to the debug service: ws://127.0.0.1:60355/d-7F-zZtGz0%3D/ws
Debug service listening on ws://127.0.0.1:60355/d-7F-zZtGz0=/ws
 Running with sound null safety
Connecting to VM Service at ws://127.0.0.1:60355/d-7F-zZtGz0=/ws

如果有人可以提供建议，我们将不胜感激。先感谢您！

Answer 1

如果您要升级到较新的版本，可能会弹出此类警告，因为它们与较新的版本不兼容。你可以忽略它。这个警告就会消失！

Answer 2

这应该是一个非致命警告。我忽略了它。