我收到这些错误并且不知道如何修复它们。
../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart:269:14: Error: The method 'FlatButton' isn't defined for the class 'PlatformButton'.
- 'PlatformButton' is from 'package:flutter_platform_widgets/src/platform_button.dart' ('../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart').
Try correcting the name to the name of an existing method, or defining a method named 'FlatButton'.
return FlatButton(
^^^^^^^^^^
../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart:302:12: Error: The method 'RaisedButton' isn't defined for the class 'PlatformButton'.
- 'PlatformButton' is from 'package:flutter_platform_widgets/src/platform_button.dart' ('../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_button.dart').
Try correcting the name to the name of an existing method, or defining a method named 'RaisedButton'.
return RaisedButton(
^^^^^^^^^^^^
../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/flutter_platform_widgets-1.20.0/lib/src/platform_dialog_action.dart:171:14: Error: The method 'FlatButton' …