You stated that you are using the Bugfix mod and AricsExpansion but you didn't say which version of his mod you are using. If you are trying to play the current public version of Aric's mod, then you will need to use the current version of this mod.
Also, Aric's mod has a lot more bugs than my mod and based on the line number in the error it's probably a bug in his mod, though possibly one from a prior version of my mod.