Zero or less rods still in inventory?

[thehman03]

I was building some windows outside of QM when i came across this:

A set of metal rods, useful for constructing grilles and other objects, and decent for hitting people.
It is a normal-sized item.
There are -2 rods in this stack.

Im not sure why this is happening but i can hold the negative rods in my hands and try to build with them. It just says i need at leat 2 rods to build a grille.