Crash app when submitting an expired joincode

[WannesMaes]

Description Made a game and copied the joincode. Started the game (1 player), played for a question, then left the game in a correct way. Tried to join the game (that doesn't exist anymore) and came on a black screen. After that i couldn't go back (no button on screen or with the android back button). Only choice close the app and start again. Afterwards i tried again, came on the same black screen, but the android back button works this time.

Possible improvement

• Check the correctness of the joincode, if not correct, then don't go to the next (black)screen and display an error message.
• If not in a game: catch all unhandled errors and go to the homescreen and display an error message.
• If in a game: catch all unhandled errors and go to the joinscreen, prefill the joincode with last game joincode and display an error message.

[TNelen]

Normally there should be a popup 'This group does not exist but it seems like this error is not caught and the popup is not thrown correctly here. This worked in previous releases.

[TNelen]

First step made in 39b6a45c7b283b14580e48b03a2944cded1f4225