Now there's something I haven't thought about for years. When in SE Asia for uncle sugars follies we had wardrobes(being generous there) with a small bulb in it to prevent mold & mildew. In more than two year no one in the platoon had any problems with it.
In a smallish cabinet even a 71/2 Watt lamp would do.
Good one, "uncle sugar's follies " is a new one for me. We had no light bulbs in ours. You just did our best to protect things from dust during the dry season. Think dry Georgia clay with the consistency of talc.