This finally happened to me. I conquered a neutral klackon city and after capturing it (not razing it) there was a blank tile in my stack of units in the city. When I right clicked on the blank tile the game crashed. I will try to fix this.
I think this is resolved now. The issue was that raider cities did not initialize the "producing unit" field correctly, so when you conquered a raider city, the city would immediately produce a unit with an uninitialized value, which showed up as a blank tile and immediately crashed the game if you interacted with it. The fix is to always initialize the "producing unit" field for every city.