Reproduction Steps

My friend and I are having the problem that minecraft locks after some time after loggin in to the german server gommehd.net. I additionaly found out that this just happens after switching to a minigame server and then back to the hub and going to the spawn.

1. join gommehd.net.
2. select a minigame from the navigator (for example "CityBuild") and click the NPC to connect to the server.
3. type /l to go back to the hub.
4. open the navigator once again and select "Spawn".
5. minecraft locks up

Crash Report File
https://gist.github.com/GameWithJerry/b2a7dc419a73033d03a36bc92cf08bdc