Wrong error message when a server is unavailable
Spark is giving the same "wrong username/password" error when the server is unavailable (offline). It should give an error that server is unavailable instead.
Have merged your PR and added a few translations and fixed wording a bit. Also tweaked the server unavailable check, so it would give the can't connect error instead of the unknown error when server is down.
So, it looks like the code would look at instanceof XMPPException for a matching condition. However it appears that most of the exceptions are being throw to SASLErrorException and SmackException.
It looks like none of the Exception conditions are working in LoginDialog.java, and everything is his hitting the default message, "Invalid username or password"
The default message should probably be changed to "Connection Error" or something similar and generic.