They’re making a joke, riffing off the “you let the magic smoke out” joke used in hardware repair. The “magic smoke” is when the chip fries and needs to be replaced, and mending can only physically repair magic items.
Mending was my first thought, admittedly because of Harry Potter And The Natural Twenty. D&D munchkin gets mis-summoned into Hogwarts, and spends a few hours every evening doing all the stuff the rules as written say his character can fit into an evening. He's still incapable of any magic the school teaches, but now he's got a bag of tricks a mile deep, and his robes look fucking incredible.