Invalid ammo of none bug

Just added UPS upgrade to my Soldering Iron, and the first time using it gave me the following bug:

DEBUG : Tried to set invalid ammo of none for soldering iron+ (UPS)

FUNCTION : item& item::ammo_set(const itype_id&, long int)
FILE : src/item.cpp
LINE : 282

Thanks for all the hard work! This might be the best game I have ever played!