Plugins fails completely

[eDexiam]

Description
In a group when someone has the Dungeon cooldown (Which is 1 hour for my case) and we start a game it completely bricks the whole plugin, leaving us stuck in the lobby.

Reproduce

1. Make a group and invite someone
2. Play the dungeon once and finish it
3. Make a new group and invite them again
4. Press the ready sign and wait for the countdown
5. They get an error saying they can't play this dungeon again for X hours
6. The plugin bricks itself

Expected behavior
The plugin to not lock up

Screenshots / GIFs / videos

https://pastebin.com/XNLxnNth

[eDexiam]

Found another way to reproduce:

Reproduce
Disband a group while being in the lobby of a Dungeon

[Sataniel98]

Thank you for the report.