Add error description and button to copy stack trace to web UI

[Gargron]

[ClearlyClaire]

glitch-soc has something like that for stack trace, but it isn't terribly useful as the stack trace is on the minified code and isn't mapped to the source-map

[shleeable]

Another PR, another killed mascot.

[witcheslive]

Now we all know how the Mastodon went extinct 😭

[Gargron]

The elephant graphic is shaped irregularly which makes it very hard to position next to text in a way that looks clean, and its color scheme is not meant to be next to red error text, as the graphic was originally designed for in-column errors accompanied by greyed out, short phrases.

I think ultimately it's more important to say in clear words that the page crashed and what can be done about it than to show a cartoon elephant.

[witcheslive]

Just giving you a hard time mostly, I absolutely do agree that the current behavior is not ideal and somewhat confusing, though it would be nice to have a mascot on there as it is somewhat calming and also fairly common. Even on this fine web sight there's the git cat making joke about the star track: https://github.com/l;asjdf;'asjf

I don't know what the possibility or budget is for perhaps doing a new mascot that fits an error page better, but it should be considered probably.

[koyuawsmbrtn]

I think this looks very clean and professional. This way normies really know that the site crashed and not that their computer might went bonkers.