Shooting a tank while it does something else crashes the server.

[Leonardo2718]

If tank A shoots tank B and, at the same time, tank B moves, shoots, etc. the game server crashes.
This occurs when server first processes tank A shooting tank B. Tank B is therefore removed from the game. However, the next message processed is tank B performing its action, by which time it is no longer in the game. So, the server throws an exception and crashes.

This can be easily fixed by not throwing an exception when a tank that no longer exists makes a move. However, doing so may introduce other, unexpected bugs.