show instead of "Exception: You must pass a root element to the UI.Create functions" the line the error occured in
The way it is currently, you get a error like this:
pcall failure in callback function ret=-1 Error: Exception: You must pass a root element to the UI.Create functions"
saddly this does not show in which line the error happens, so if there are multiple places where you use UI.Create it is nearly impossible to track this bug if you were not the person who experienced the bug.
AdminDanWL (Admin, WarLight) commented
You could try commenting out IU calls until it works. Really not ideal though.