Thank you for giving it a spin! And for the bug report too, hrm. I'm not sure where to begin unpicking that since it seems like an interaction across multiple code sections and how it's interacting with running on the browser? I'll peck at it and see if I can reproduce and start sorting it out. Or at least, stop it from occurring in later projects (I don't always remember to test the options scene, so I'll make a note on it).
Taking a quick swing at it, I don't get an error opening and then canceling the options screen (it loops back to title as intended), but I'll have to try it from a clean cache. If it's some kind of storage issue it might not trigger if there's already like, successfully stored information (or at least, that being true rules out the storage issue). What browser did you get this issue with? It might not be pertinent, but it's the first thing I can think of.