Multiplayer Diplomacy Crashes the Game

Jonasfull#5486

Two Players opening Diplomacy at the same time Crashes the game. Sure we can tell the other player not to open diplomacy while the other one wants to open it, But during the end of a turn there's a chance A.I Will include both of us in their Diplomacy screen and that will prevent the game from Continuing.

Khornesh#1729

Same here.
Tried to build outpost - got crash.
My friend declared war and asked me to join - got crash.

So far we l didn't found how to play game in coop in such circumstances.