Hi Mitch,
That error doesn't look familiar to me. I searched our source code and couldn't find any reference to it. I also searched our case history and it doesn't look like anyone has reported this before.
I'm wondering if there is some browser plugin that is injecting javascript like Tampermonkey or Greasemonkey.
One way to quickly rule this out would be to open an Incognito window and see if it pops up in there too since most browser extensions aren't allowed to run in Incognito modes.
Beyond that, I think we'd like to probably get on a webex to do some additional analysis.