/D:/flutter/.pub-cache/hosted/pub.dartlang.org/video_player_platform_interface-2.2.0/lib/messages.dart:4:1: Error: A library can't opt out of null safety by default, when using sound null safety.
// @dart = 2.8
^^^^^^^^^^^^^^
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:
package:camera
package:story_view
package:flutter_cache_manager
package:video_player
package:rxdart
package:video_player_platform_interface

// @dart=2.9
import 'package:flutter/material.dart';
void main() {
  //...
}