SyntaxError: Unexpected token '<'

I happen to be in Twine (version 2.4.1), I just tried some words to test in HTML, and when I open it, I get this error box in my Chrome browser:

I don’t know what’s going on and I’m starting to think it might be some bug, I’ve researched that it’s an error in the Javascript commands but trying to change it seems a bit impossible or I don’t know how to make it stop appearing.

Any help will be valuable!

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