The first error isn't a bug. You just failed to look at the folder inside of the Aric's mod folder called IMPORTANT - READ THIS BEFORE INSTALLING and following the instructions contained within there. Part of which includes dropping in that specific file because it doesn't exist in the base game.
Not entirely sure how the other one would be coming about though because Aric's Expansion doesn't change that line or anything relating to what is stored in the variable. Would recommend following the instructions on the install and then seeing if it goes away.