This add-on is totally not web development friendly. If for some reason you choose not to offer user+password remembering functionalities on localhost / non encrypted connections, you should be decent enough to fallback your user to default Firefox functionalities.

Addon not working in the Mullvad browser. (file appears to be corrupt error) I know, the service is on beta and this is a browser that uses firefox "framework" and is not necessarily Firefox. However I'd like the service to at least be accessible from web address (to consider adopting the service). I am not installing Firefox instead, as it would kill the entire purpose of a privacy-focused environment.