I also am not familiar with these packages at all, but I wanted to chime in and offer both condolences and encouragement, as this is an error that I regularly find myself hitting and which you will probably see again. I think you are in good company, though, and not just of people new to R 
Basically, somewhere a $ is getting fired on something or in a way that it shouldn't be. I usually end up debugging it by digging in more intentionally into the objects I am working with, simplifying my example, or breaking out "one liners" into more complete chunks.
i.e. in your case, I would take the rulesMatchLHS object, play with it, try t1 <- lhs(rulesMatchLHS), and maybe t2 <- labels(t1). Eventually, I'd get around to the $ and try to understand what is breaking where.
Not sure if it helps, but definitely don't give up! If I had a nickel for every time I got through this error... I'd have a lot of nickels. I think I saw it yesterday... You will do it!
(Aside: your github repo may make this possible, but digging into the skills of creating a reprex is probably one of the single most valuable skills you can develop as a learner! It helps you not only isolate your problem, but ask better questions that others can dig into. It is particularly helpful when you run into a bug in a package that you do not maintain or any hard-to-explain behavior)