This is for the 02FEB13 Release.
When using a firearm that has an attached extra magazine, reloading the extra mag causes the following error:
DEBUG: Attempted to access item -2 in an inventory (size 42) Press spacebar…
That is to say when I have the extra magazine attached to a gun and the first one runs dry, reloading causes that error prior to loading the second magazine into the gun. It still reloads like it should however it generates this error every time.