4. M-x flymake-mode
3. goto-line 240 or 568 at js.el
(there is warning around here, basically putting a space before end of the line
cause similar warning in docstring)
5. you can check it by flymake-goto-next-error, but it isn't visible.
Not sure this is related, flycheck highlight previous word with the same error.
(checked on Emacs-26 branch and pulled 75bb482. This time I used bootstrap option)