No longer works in a browser

**Describe the bug**
The latest version of ffmpeg.wasm no longer works in a web browser: the 'ffmpeg.FS' function tries to fetch files from the non-existent path.

**To Reproduce**
Steps to reproduce the behavior:
1. Load the latest version of the library from a CDN in your html file, for example:
``

2. Now, add the following script (but any script involving the filesystem function will produce a similar error)
```

const {
createFFmpeg,
fetchFile
} = FFmpeg;
const ffmpeg = createFFmpeg({
log: true
});

const demo = async () => {
await ffmpeg.load();
ffmpeg.FS('writeFile', 'audio.ogg', await fetchFile('../assets/audio.ogg'));
}

demo()

```

3. Open the devtools console (F12) and the following error will be logged there:
> GET /home/jeromewu/repos/ffmpeg.wasm/src/assets/audio.ogg net::ERR_FILE_NOT_FOUND

The library tries to fetch files from the non-existent path instead of using the path on your server like it did in previous versions.

❌/home/jeromewu/repos/ffmpeg.wasm/src/assets/audio.ogg
✅ localhost:8080/assets/audio.ogg

For example, the older version of the library in this official repo https://github.com/ffmpegwasm/chrome-extension-app/tree/master/vendor will load its resources from correct path.

**Expected behavior**
The library fetches file from the correct path on your server instead of using the '/home/jeromewu/repos/ffmpeg.wasm/src/assets' path.

**Screenshots**

**Desktop (please complete the following information):**
Chrome 114