Uncaught Syntax Error: Unexpected Token Var

Every time I join a table, after the "welcome" message pops up, a message that matches the title of this post appears and is followed by a long string of characters. On some tables (specifically fortysecond and hustle's tables)it does not pose a problem other than placing a horizontal scroll bar at the bottom of the chat window, but on other tables (specifically triclopyr's table) it prevents me from seeing any new messages (including my own). I'm not sure when exactly this bug began, but it simply started happening one day and hasn't stopped since.
My browser version is: (do not change)
Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36

I think it's worth noting that the problem only occurs on Chrome, but Firefox works fine.

You might try disabling your Chrome plugins one at a time to see if any of them are causing the issue.