I just wanted to share my solution to the problem.
I was getting the error only when I had WooCommerce enabled, so of course I figured that WooCommerce was the source of the problem.
I made the changes that were talked about in the other threads (removing the lines with the error message) and I was strangely still getting the error. I ended up doing a search in my theme's folder, and it looks like they also have some blockUI code in their js (that was only enabled when I had WooCommerce enabled). The exact file was in the theme folder in /scripts/pix_woocommerce.js, although it might be different for you.
So check your theme folders for the error message too! :)