Flutter 升级后我开始面临这个问题。3.0.1
\n该应用程序可以运行，但终端中出现错误（警告）。
\n这似乎是一个绑定问题。
\n错误（警告）说：警告：空感知操作'！'的操作数 具有排除 null 的类型“ScheduerBinding”。
\n/C:/Software%20Utilities/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_math_fork-0.5.0/lib/src/widgets/selectable.dart:459:24: Warning: Operand of null-aware operation '!' has type 'SchedulerBinding' which excludes null.\n\n- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('/C:/Software%20Utilities/flutter/packages/flutter/lib/src/scheduler/binding.dart').\n\n SchedulerBinding.instance!.addPostFrameCallback((_) {\n\n ^\n\n/C:/Software%20Utilities/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_math_fork-0.5.0/lib/src/widgets/selection/web_selection_manager.dart:119:24: Warning: Operand of null-aware operation '!' has type 'SchedulerBinding' which excludes null.\n\n- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('/C:/Software%20Utilities/flutter/packages/flutter/lib/src/scheduler/binding.dart').\n\n SchedulerBinding.instance!\n\n ^\n\n/C:/Software%20Utilities/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_math_fork-0.5.0/lib/src/widgets/selection/overlay_manager.dart:138:28: Warning: Operand of null-aware operation '!' has type 'SchedulerBinding' which excludes null.\n\n- 'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('/C:/Software%20Utilities/flutter/packages/flutter/lib/src/scheduler/binding.dart').\n\n if (SchedulerBinding.instance!.schedulerPhase ==\n\n ^\n\n/C:/Software%20Utilities/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_math_fork-0.5.0/lib/src/widgets/selection/overlay_manager.dart:140:26: Warning: Operand of null-aware operation '!' has …