@rainy
I have done tests after you mentioned. But i haven't meet the issue. Maybe there are some other reasons cause the crash.
I recommand trying some ways to avoid, such lowering the visual effect resolution, using the vulkan mode, changing the heapsize.

Bug report! If you have the full Fazclaire set installed (for both sets of survivors) and try to pick up a melee and swap to either the magum/pistol/other melees the game will crash