The thing is that one of your slaves equipped with an item which no longer exists. Try to go through them all to fix it. I'm not sure what causing it in first place though.
I have unequipped all items from all slaves and the main character. error persists these error messages popped in as I did
https://www.4shared.com/file/DQR-K5IHei/energy_clitch_fix_attempt_2.html