What is unlikely candidate in chrome inspector console?

Question

Google Chrome

I would like the inspector not to show any errors when submitting the project. But now something is displayed that I cannot understand and google:

Who knows what it is, and why does it arise?
The name of the class changed - the notification does not disappear.
footer-bottom
footer-blah
footer2-bottom
foot-bottom
bottom-foot
the same result
already on foo-bottom does not swear
why he doesn't like the class name with the word footer?

Answer 1

My guess is that it uses a floating block that follows the scroll and stops when the footer is found. Well, it displays the fact of its existence in the console.
It is likely that the error is not related to this unlikely candidate.