If a WorkingTree was initialized, then a few leaf nodes were inserted and saved, and the WorkingTree was also saved. If then the Working Tree was deleted, the Nodes would still exist in the database and take up space.
https://github.com/initia-labs/opinit-bots/blob/640649b97cbfa5782925b7dc8c0b62b8fa5367f6/merkle/db.go#L14-L23
