I was trying to swap my pistol from hands to inventory for one of it's mags.

The weapon vanished from hands/inventory, the mag gone to my hands though.
Then I tried to switch the first mag to the second one. The first got stuck inside the second mag item slot in the inventory.

Then the whole character bugged out as if he got items stuck in-hands.

I couldn't swap anything to my hands from hotkey, so after a while messing with this inventory management problem, trying to "unstuck" my hands (Pressing F2, F5 multiple-times, jumping) the game crashed, and I didn't came back again as it was late over here.