Extension chokes on sourcemap when debugging addons

Hi,

I'm trying to debug a simple FF add-on that I'm packaging with Parcel. *vscode-firefox-debug* loads the extension and it runs fine. The problem is I'm unable to set/hit break points.

I played around with many launch configuration *pathMappings* combinations without success. I then enabled logging in the launch definition and I now get the following error report when I start a debug session:

```
INFO |000.178|PathConversion: Can't convert url data:application/json;charset=utf-8;base64,eyJtYXBwaW5ncyI6Ijs7...
```

The problem URL is the data sourcemap URL added at the end of the associated JS file packaged by Parcel.

I don't think the sourcemap URL is corrupted as I can load the Parcel generated JS files using the VSCODE *colder.source-map-visualization* extension without complaint.

Is there a work round for this?

Cheers, Steve

まず、Parcel でパッケージ化された Firefox アドオンのデバッグセッションを再現し、起動定義の pathMappings とログ出力を調べます。生成された JavaScript に追加された data:application/json sourcemap URL の PathConversion による処理を追跡します。セッションが sourcemap を受け入れ、ブレークポイントを設定してヒットできれば完了です。

索引モデルが issue の本文から書いたものです。