Web-greeter seems to crash if LightDM doesn't define a default language

[TLATER]

I'm not sure how I managed to construct a system that doesn't have this set, but it can happen according to the pygobject API reference, so this once it hopefully isn't only me.

Should this occur, we hit this code with lang set to None - I get a constantly-restarting lightdm as a result, having to rely on journalctl -xe to even see the exception.

[TLATER]

Hmm, upon closer inspection it appears that this happens if no system locale is set.

The "workaround" is setting the system locale (localectl is your friend), but it would probably still be nice if overlooking this didn't cause lightdm to crash in a mysterious way.

[lots0logs]

I'm not sure I'd consider this a bug though if it is a bug, it's a LightDM bug (not web-greeter).

[TLATER]

@lots0logs I don't think I agree with that assessment - it's a perfectly valid state for the system not to have a default language set - LightDM decided to signify that state by returning None. It would be a LightDM bug if LightDM crashed in that case.

The issue is that web-greeter does not handle this state correctly - it should probably, instead of crashing, either use some hardcoded default language or prompt the user to choose one.