升级到flutter 3.0.0后，在运行应用程序时开始出现问题，
(The应用程序工作，但终端中出现错误（警告））。
这似乎是一个绑定问题。
错误（警告）显示：警告：可识别null的操作“！”的操作数具有排除null的类型“WidgetsBinding”。

: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
../…/src/keyboard_visibility.dart:21
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../fvm/versions/3.0.0/packages/flutter/lib/src/widgets/binding.dart').
package:flutter/…/widgets/binding.dart:1
    WidgetsBinding.instance!.addObserver(this);

                   ^
: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
../…/src/keyboard_visibility.dart:37
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../fvm/versions/3.0.0/packages/flutter/lib/src/widgets/binding.dart').
package:flutter/…/widgets/binding.dart:1
    WidgetsBinding.instance!.removeObserver(this);
                   ^
: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
../…/src/bot_toast_init.dart:15
- 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../../fvm/versions/3.0.0/packages/flutter/lib/src/widgets/binding.dart').
package:flutter/…/widgets/binding.dart:1
    WidgetsBinding.instance!.addObserver(this);
                   ^
: Warning: Operand of null-aware operation '!' has type 'SchedulerBinding' which excludes null.
../…/src/bot_toast_manager.dart:6
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('../../../fvm/versions/3.0.0/packages/flutter/lib/src/scheduler/binding.dart').
package:flutter/…/scheduler/binding.dart:1
  SchedulerBinding.instance!.addPostFrameCallback((_) {
                   ^
: Warning: Operand of null-aware operation '!' has type 'SchedulerBinding' which excludes null.
../…/src/bot_toast_manager.dart:9
- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('../../../fvm/versions/3.0.0/packages/flutter/lib/src/scheduler/binding.dart').
package:flutter/…/scheduler/binding.dart:1
  SchedulerBinding.instance!.ensureVisualUpdate();

编辑：****-此问题与某些包与flutter 3.0.0的兼容性有关

• （Flutter 3中有一些变化，所以现在包的作者应该会赶上这些变化）。

Flutter 3.0.0发布说明
如果您看到关于绑定的警告迁移到Flutter 3时，您可能会看到如下警告：
Warning: Operand of null-aware operation '!' has type >'SchedulerBinding' which excludes null.
-例如bot_toast软件包https://github.com/MMMzq/bot_toast/issues/133的GitHub存储库中有一个未解决的问题，因此应该在发布更新后尽快修复该问题。