Same for me on Chrome v77 (both macOS and Linux), it was working fine on v76 on macOS few minutes before I upgraded to v77. I see the same error in console for docs.discourse.org page reported in the OP.
I came here because, in addition, one of the topics on my self-hosted Discourse instance is just spinning on v77 (observed yesterday on Linux and just now on macOS). Same behavior as that topic loaded perfectly fine on v76 before I updated. This one just keeps spinning and has not even gotten around to printing the error on the console. The only peculiar thing about this page is that it has had dozens of wiki edits. Rest of my site seems to work fine.