I did some searching and found out that that error only happens when you're using a mod that requires an EP you don't have.

That doesn't add up. I have all EPS and SPs and the error was when a sim went to pay at a cash register for an OFB home business, right when the caching sound and simoleons were supposed to pop up indicating funds were added to the household.

The items being sold are an expensive crate of Mouthwatering Strawberries, packed with the SimWardrobe packing station.
After repeatedly getting this error, I used the Batbox to nuke/fix things and forced errors> on all. Nothing.

The included screenshots might help.

It can mean that, it doesn't only mean that. What it means is it's trying to refer to code which isn't there or the game can't find (that's why it happens when you use the wrong EP version of something) - it can also be trying to look for code in another mod which you don't have, for example.

I would look around to see if you can find anything about the SimWardrobe crates and OFB - I am fairly sure you will find the problem there. I have a feeling I might even have seen something about it at simbology but I could be wrong.