The Repair Kit under Equipment adds a boost to the Craft (Mechanical) skill. If a user adds it when they don't have the Craft (Mechanical) skill (which I did by accident), it displays an error message saying that skCrafMech doesn't exist every time you add a piece of equipment. You may want to change it to a more graceful message, or simply avoid running that bit of code if they don't have the skill. I suspect multiple kits will be affected by this.