title: Unexpected Exception when using ffmpeg.wasm in Chrome extension
body: <p>I'm trying to implement a chrome extension which allows me to play <em>flv</em> videos by transcoding them to <em>mp4</em> and then inserting a video player as it's done on the <em>transcode</em> example from <a href="https://github.com/ffmpegwasm/ffmpeg.wasm" rel="nofollow noreferrer">ffmpeg.wasm</a>.</p>
  <p>As chrome extensions don't support the execution of downloaded code, I need to use a downloaded version of ffmpeg-core.
  I've downloaded the 0.8.4 version and included the folder on the manifest under <em>web_accessible_resources</em>, so that on the javascript file for trancoding the code is:</p>
  <pre class="lang-js prettyprint-override"><code>const { createFFmpeg, fetchFile } = FFmpeg;
  const ffmpeg = createFFmpeg({
    log: true,
    corePath: chrome.runtime.getURL('ffmpeg-core/ffmpeg-core.js'),
  });
  
  const transcode = async (file) =&gt; {
    const { name } = file;
    console.log('Loading ffmpeg-core.js. Transcode URL.');
    await ffmpeg.load();
    console.log('ffmpeg-core loaded.');
  
    let blob = await fetch(file).then(r =&gt; r.blob());
    console.log('blob downloaded');
  
    ffmpeg.FS('writeFile', name, blob);
    console.log('Start transcoding');
    await ffmpeg.run('-i', name,  'output.mp4');
    console.log('Complete transcoding');
    const data = ffmpeg.FS('readFile', 'output.mp4');
  
    const video = document.getElementById('output-video');
    video.src = URL.createObjectURL(new Blob([data.buffer], { type: 'video/mp4' }));
  }
  </code></pre>
  <p>Once the <em>transcode</em> function is executed, I get the following exception:</p>
  <pre><code>ffmpeg.min.js:1 Uncaught (in promise) TypeError: t is not a function
      at ffmpeg.min.js:1
      at f (ffmpeg.min.js:1)
      at Generator._invoke (ffmpeg.min.js:1)
      at Generator.next (ffmpeg.min.js:1)
      at i (ffmpeg.min.js:1)
      at c (ffmpeg.min.js:1)
  </code></pre>
  <p><img src="https://i.imgur.com/k8hdsxS.png" alt="" title="Log" /></p>
  <p>Does somebody have any idea of why could this be happening?</p>
  <p>Thanks a lot!</p>