Indefinite wait if relay no longer exists
While replacing the metrics and torstatus links on the bad-relays page [1] I noticed that atlas hangs indefinitely when you go to a page for a relay that no longer exists. For instance... https://atlas.torproject.org/#details/FFD2075CC29852C322E1984555CDDFBC6FB1EE80
The animated gif gives the impression that it's still doing something, but that's probably a lie. We should display something saying that the relay no longer exists. Ideally we'd tell them when the relay was last around and a snapshot of its state, but if that isn't possible then getting whatever assurance atlas can provide ('that relay has been offline for the last X days') would still be preferable to what it has now.
[1] https://trac.torproject.org/projects/tor/wiki/doc/badRelays