Oh wow, that error handler actually found something? The problem should be that some other mod has coded an item with a normal/expensive split, but has not defined either the "normal" or "expensive" part of it. I'm assuming the mod in question is rampant? Am currently making a new modpack to play, so I might as well test this now myself.
EDIT: The item being referenced is definitely from rampant, however I was unable to cause this error, even with full bobs-angels-omni and rampant. The item in question is also defined properly in their code, as far as I can tell. Maybe I broke my logic somewhere... or it could be caused by redefinition of recipes from something...