I had a farmer killed by a werebeast, and apparently the body was not properly buried. The farmer rose as a ghost and claimed a tomb zone (the tomb zone became assigned to that unit without any input from me). If I remove the zone, the game reliably crashes soon afterwards.

In the save, the zone in question is the middle coffin on the farming level (the screen is centered on it when you load the save). Hit z to bring up zones, remove the zone, and unpause the game. The game should crash quickly,

If you unassign the unit from the zone before removing the zone, the crash does not occur.

I am running the testing version for SDL2: 50.09sdl2-2
no mods