Okay so if you encounter a bad map and it fails to load you return back to geoscape... After that you wont be able to play any other mission until you quit the game completely and relaunch it. If you try to launch a mission you will be staring at a black screen.
Only thing I got on the debugger console was:
Could not spawn the map
Oh and game isn't locked. You can pull down the debugger console at will and even issue commands like "quit".
