Klaus-Dieter Bauer <bauer.klaus.dieter@gmail.com> schrieb am Sa., 26. Nov. 2016 um 00:13 Uhr:

Hello!

In `emacs-lisp-mode', the counting of the nesting level of forms seems
to be broken in some subtle way. Consider e.g.

(form
(
) WEIRD HIGHLIGHT
x) ;; Unexepected Indentation

It looks like "WEIRD HIGHLIGHT" is wrongly highlighted as junk after a
surplus closing parenthesis, and the subsequent form is also weirdly
indented.

This is working as intended (i.e. not a bug). Lisp-mode explicitly tests for this. When you hover over the highlighted part, you get a tooltip "Hidden behind deeper element; move to another line?"

While not a syntax error, there's such a strong convention to avoid such formatting that the Lisp modes warn unconditionally about it.