Why this would be helpful/solve a problem

Recently, someone had a situation: #5289 where their installation of SA would not load its setting page or its addons:

I'm sure this has happened to several users, and while from the perspective of each user it is a rare occurrence, it's a rather severe bug and is happening frequently enough to prioritize.

In the example above and in a few of the bug reports I've seen, this error message was present:

Unchecked runtime.lastError: IO error: .../LOCK: File currently in use. (ChromeMethodBFE: 15::LockFile::2)

Doing a quick search, this may be resolvable with a browser or computer restart.

Proposal

There should be an indication of what went wrong and some way or guide to fix the problem, anything from a tip to restart the browser to a way to get your settings file, or maybe even a way to start over and reset Scratch Addons back to factory settings for those who wouldn't mind.

Possible alternatives

We can discuss other ways to solve this on #5291.

Demonstration(s) and additional context

Nothing else to say.