Can you try just setting the weapons you have on that map on a new flat map and set up a few lights as you have them in the map level that gave you there error.
I suspect that it may have something to do with that as, that is where the log stopped when you posted here. the log has a few attempts at Light mapping already but no code as this reported. I see the error call code, in the log, so this might be the clue to which object it is, and I think it is the ammo, so include that also on the test map please.
Thanks
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