[Fixed - persists in 3.80] Integer overflow?

[JP_Finn]

My character got tired of taking skis off to climb trap fence to get small game trap caught critters on the other side. Decided to Deconstruct a section, replace it with gate.
So I used Make-Build-Deconstruct. Moved to the hole in fence, pushed the stakes and withes tile south. moved out of way and built gate with Make-Build-Gate. As the character had 4 stakes and 2 decent and 2 inferior withes in their inventory, I know there's 2 of each extra needed for a gate (carrying material for another gate for another fence).
I didn't expect to see withes left on the ground. Much less to see 65534 Fine withes on the stack on the ground!

Emailing save.

[Sami]

This was a tricky case, but luckily it's found and fixed now. 
There was a clear math failure which manifested itself not always but in rare occasion as with this character's whereabouts.

Fixed - persists in 3.80.