Script doesn't execute, pr###mably due to syntax error.

Running Waterfox Classic's latest version and the latest version of Tampermonkey, but this script broke for me a while back and hasn't worked since. Reading someone else's issue, I think I can cut and paste the syntax error listing from my browser console, as follows:

This should work in r65. FYI, the issue is that this browser is really far behind mainstream browsers and is missing script features that have been available for about a year and a half, so you might run into other issues with that browser...