It hops if it fails to solve the library as a fail safe. The bot is based on the runelite plugin solving methodology and it isn't perfect. If that is happening multiple times in a row or with any real regularity, there's probably some plugin-related problem going on. Are you running on a default runelite profile with no other plugins running?
Oh, it will do it regularly if you haven't progressed the depths of despair to the point of being sent to the library. Have you done that? I've copied the warning from the overview page below:
BUGS:
* In the current version, this bot will get stuck if you have not partially completed The Depths of Despair up to the point of getting the book from the library. I am working on a fix now. Doing the required portion of the quest involves talking to two NPCs in Hosidius before they send you to the library. It's very fast.