我发现这个错误来自于在jQuery上下文中对事件“e.data“变量的调用。做一个简单 AJAX XHR很快就解决了这个问题...

const xhr = new XMLHttpRequest();
xhr.open("POST", 'upload.php', true);
xhr.send(fileUpload);

把它放在一起...它现在工作没有错误！

navigator.mediaDevices.getUserMedia({
    audio: true
  })
  .then(function(stream) {
    audioStream = stream;
    recorder = new MediaRecorder(stream);

    const chunks = [];

    recorder.onstop = (e) => {
      const blob = new Blob(chunks, {
        type: "audio/wav;codecs=MS_PCM"
      });
      var fileUpload = new FormData();
      fileUpload.append("fileToUpload", blob, "audio.wav");
      const xhr = new XMLHttpRequest();
      xhr.open("POST", 'upload.php', true);
      xhr.send(fileUpload);
    };

    recorder.ondataavailable = (e) => {
      chunks.push(e.data);
    };

    recorder.start();
  });