Experiencing a similar issue, but wanted to pitch in what I’ve learned in my testing.
I’m only getting this error on Windows.
My site remains live but I can’t access the dashboard nor Designer on my PC, and the lightboxes on the site (only interactive element I have other than page link buttons) are unresponsive. Even after disabling Adblock Plus, clearing cache, and deleting cookies these issues seem to persist.
All is working normally on Mac.