Today it crashed again, but this time I got a different message:
atanks: src/virtobj.cpp:77: virtual void VIRTUAL_OBJECT::draw():
asserzione "bitmap && "ERROR: VIRTUAL_OBJECT::draw() called without
bitmap!"" non riuscita.
Shutting down Allegro due to signal #6
I don't know if it's the same bug or a different one. It seems both
messages (the one in my original report and this one) refer to something
GUI related, they both happen while playing, they are both failed
assertions and they both happened during the AI turn, but that's all I
have to assume they are related to the same bug.