Attempt to accept an invitation to an album you are already in: Bad messaging

[crspybits]

You get an alert: "Alert! Error accepting sharing invitation!" Surely I can do better than that! Something more specific. A message like "You area already a member of this album, and can't in it twice."

[crspybits]

Then, I did a refresh on the Albums screen and got "Alert! An error occurred". From the console in Xcode:
Server error occurred: otherError(SyncServer.SyncServerError.non200StatusCode(401)) [syncServerErrorOccurred(error:) in SyncController.swift, line 506]
It looks like that failure to accept the sharing invitation signed the user out (which is odd and inappropriate) and also left the user on the Albums screen.

Then, I attempt to sign in to the same Facebook user as an "Existing Account", and I get "Alert! Somehow a Facebook user attempted to create an owning user!!".

[crspybits]

OK-- Now I've fixed the second part of this issue. Now the refresh on the Albums screen succeeds etc. Still need to fix the "Alert! Error accepting sharing invitation!" but that will require a change in the server to return more informative HTTP status codes (for example).