Improve generic error handling

[kjetilk]

There have been issues with the "Log In" button in the popup being unresponsive. I still have this problem, nodeSolidServer/node-solid-server#884 and others had this problem due to an expired cert.

There should be some kind of feedback to the user in this situation, at least an error that they can go to the forum about. Perhaps there should even be a forum link in the error message if it is very generic?

[RubenVerborgh]

I think the problem is that the feedback never reaches the client code. Fetchers in the browser are not allowed to see many details about request failures, as these can be exploited.

But I can probably set a timeout that results in an error message.

Can someone post exact steps to reproduce?

[kjetilk]

Hmmm, but in my case, it happens without any network interaction, and it only happens on my laptop, so it is clearly highly environment dependent... Awfully hard to reproduce... I'll tinker with some plugins and see if that matters, at least.

In JD's case, they had an invalid cert on the WebID provider. Presumably, it can be reproduced simply by having that. These are two very different bugs, but I was hoping there could be some generic fallback error handling...