decodeAudioData' of undefined

p5.js Libraries
1

Hi, I was trying to rewrite some code and then I started getting an error

Uncaught TypeError: Cannot read property 'decodeAudioData' of undefined at FileReader.reader.onload (lvl.js:131)

on this line

       this.context.decodeAudioData(fileEvent.target.result, calcTempo);

How I can fix it?

function Lvl(song){
  this.Engine = Matter.Engine;
  this.World = Matter.World;
  this.Bodies = Matter.Bodies;

  this.engine;
  this.world;

  //physObj
  this.walls = [];
  this.player;
  this.snake = undefined;
  
  //par for obj
  this.playerRadius = 45;

  //array for draw
  this.drawebleObjects = [];

  this.screenSize = createVector(windowWidth,windowHeight);

  this.canvas;

  this.bar;

  this.isStarted = false;

  this.ground;
  this.up;
  this.left;
  this.right;

  this.root;

  this.loadingTicks;

  this.create = function(){
    this.root = document.documentElement;
    this.engine = this.Engine.create();
    this.world = this.engine.world;

    this.GetMt();

    this.ground = new Rect(createVector(windowWidth/2,windowHeight),windowWidth,5,0,this.engine,this.Bodies,this.world,this.World,{isStatic: true});
    this.up = new Rect(createVector(windowWidth/2,0),windowWidth,5,0,this.engine,this.Bodies,this.world,this.World,{isStatic: true});
    this.left = new Rect(createVector(0,windowHeight/2),5,windowHeight,0,this.engine,this.Bodies,this.world,this.World,{isStatic: true});
    this.right = new Rect(createVector(windowWidth,windowHeight/2),5,windowHeight,0,this.engine,this.Bodies,this.world,this.World,{isStatic: true});
    this.bar = new BonusBar(createVector(0,0),color(153,102,204),10,1);

    this.Engine.run(this.engine);
  }


  this.show = function(){
    background(28);
    if(this.isStarted){
      
      if(this.player == undefined){
        this.player = new Krug(createVector(this.screenSize.x/2,100),this.playerRadius,0,{frictionAir: 0,friction:0,restitution:1,inertia: Infinity,isStatic:false});
        this.snake = new Snake();
        this.snake.setup();
      }

      if(this.bar._progress<5){
        this.snake.setEasing();
      }

      noStroke();
      this.player.show();
      this.snake.show();
      this.bar.show();
      noStroke();

      if(mouseIsPressed){
        if(mouseButton == CENTER){
          this.snake.createSegment(this.snake.x[this.snake.x.length-1],this.snake.y[this.snake.y.length-1]);
        }
        else if(mouseButton == LEFT){
          if(this.snake!=undefined){
            if(this.bar._progress>=100)
            {
              this.bar.rst();
              this.snake.easing=0.5;
            }
          }
        }
      }
      textAlign(BOTTOM,CENTER);
      fill(255);
      textSize(20);
      text('BPM: '+mt.tempo,50,50);
    }
    else{
      if(this.loadingTicks<6) this.loadingTicks++;
      
      else this.loadingTicks = 0;
      
      let strL = '';

      for(let i = 0;i<this.loadingTicks;i++){
        strL=strL+'.';
      }
      
      textAlign(LEFT, CENTER);
      fill(220);
      textSize(32);
      text('LOADING '+strL, windowWidth/2-((7*32)/2), windowHeight/2);
      }
  }



  //get bpm

  this.context = new AudioContext();
  this.mt;

  this.GetMt = function(){
    async function pasteAudio() {
      var blob = await (await fetch('scripts/testSound.mp3')).blob();

      dt = new DataTransfer();
      dt.items.add(new File([blob], 'scripts/testSound.mp3', {type: 'audio/mpeg'}));

      var files = dt.files;

      if (files.length == 0) return;
      var reader = new FileReader();

      reader.onload = function(fileEvent) {
       this.context.decodeAudioData(fileEvent.target.result, calcTempo);
      }
      reader.readAsArrayBuffer(files[0]);
    }
    pasteAudio();

    var calcTempo = function (buffer) {
      var audioData = [];
      // Take the average of the two channels
      if (buffer.numberOfChannels == 2) {
        var channel1Data = buffer.getChannelData(0);
        var channel2Data = buffer.getChannelData(1);
        var length = channel1Data.length;
        for (var i = 0; i < length; i++) {
          audioData[i] = (channel1Data[i] + channel2Data[i]) / 2;
        }
      } else {
        audioData = buffer.getChannelData(0);
      }

     this.mt = new MusicTempo(audioData);


      let wave1Spd = map(mt.tempo,0,350,1,25);
      let wave2Spd = map(mt.tempo,0,350,1,20);
      let wave3Spd = map(mt.tempo,0,350,1,15);
      root.style.setProperty('--spd', wave1Spd+"s");
      root.style.setProperty('--spd2', wave2Spd+"s");
      root.style.setProperty('--spd3', wave3Spd+"s");
      console.log(mt.tempo);

      this.isStarted = true;
      this.song.play();


      /*const audio = new Audio()
      audio.src = 'scripts/testSound.mp3'
      audio.play();
      textAlign(CENTER);
      textSize(32);
      fill(200);
      text('bpm~ '+mt.tempo, windowWidth/2, windowHeight/2);*/

    }
    return true;
  }


}

thanks for reading)