Checking member info for a user not in the current guild doesn't work

[eritbh]

The page loads forever, because the call for member info 404s. To do something sensible in this situation, we need to do r-anime/misato#38, but in the meantime we should at least fall back to displaying a user ID or something if we have literally nothing else to show there.

It may make sense to split the user info (name/id/avatar) display and the note/warn/etc display into their own components, each relying on a different set of requests to get the required info. We could also make the API return this info much more cleanly, but that's kinda a lot of effort.