Ok, this is what appened:

I was playing with two account on the same computer in snapshot (i was testing somethings) Player 1 launch the world in LAN and Player 2 was connected to it in multiplayer. After, Player 1 "Save and quit" so it supposed to kick Player 2 and close the LAN server. BUT, that's not what happened. Player 2 was correctly kicked, but Player 1 game crash.

Here how to reproduce:
1-Lauch to Minecraft games with different account on the same computer.
2-Do Player 2 connect in LAN to the Player 1 game
3-Do Player 1 "Save and quit"

In the attachement, there the crash report.

Thanks, and sorry if it's a duplicated.