Browser outdated warning on almost current Firefox / Linux Mint

I’ve read the FAQ, my Firefox is (almost) current (just a .0.1 missing), and the browser console does not give me any useful information.

Edit: I’ve found a few errors, had the wrong setting for the console… (:woman_facepalming: )

Web Assembly is not part of Firefox on Linux Mint.

The other error message is:
Uncaught Error: Browser does not suport ECMAScript 2017 / ES2017

Where do I go to make a request for a better error message that tells a user exactly what is wrong? This must be quite frustrating for all the Linux Mint users out there.

I’m going to use Chromium for this, I guess.