颤振：致命错误：回调查找失败！- 每当播放音频时

Question

我的应用程序运行良好，但每当播放音频时我都会收到此错误。我试图在这里寻找解决方案。他们中的大多数人说要调用这个方法“monitorNotificationStateChanges”并将静态函数传递给它。我试过做同样的事情，但出现同样的问题

import 'package:audioplayers/audio_cache.dart';
import 'package:flutter/material.dart';

void main() => runApp(XylophoneApp());

class XylophoneApp extends StatelessWidget {
  void playSound(int soundNumber) {
    final player = AudioCache();
    player.play('note$soundNumber.wav');
  }

  Expanded buttonKey({Color color, int soundNumber}) {
    return Expanded(
      child: FlatButton(
        color: color,
        onPressed: () {
          playSound(soundNumber);
        },
        child: Text(''),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        backgroundColor: Colors.black,
        body: SafeArea(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: <Widget>[
              buttonKey(color: Colors.red, soundNumber: 1),
              buttonKey(color: Colors.orange, soundNumber: 2),
              buttonKey(color: Colors.yellow, soundNumber: 3),
              buttonKey(color: Colors.green, soundNumber: 4),
              buttonKey(color: Colors.blue, soundNumber: 5),
              buttonKey(color: Colors.teal, soundNumber: 6),
              buttonKey(color: Colors.purple, soundNumber: 7),
            ],
          ),
        ),
      ),
    );
  }
}