bug#46607: 25.2; Emacs hangs with Error running timer 'blink-cursor-start'

[Eli Zaretskii <eliz@gnu.org>]

> From: Peter Flynn <peter@silmaril.ie>
> Date: Wed, 17 Feb 2021 23:09:25 +0000
> 
> For a blow-by-blow account, see
> https://emacs.stackexchange.com/questions/36612/emacs-hung-with-error-running-timer-blink-cursor-start?noredirect=1#comment99937_36612
> 
> Summary:
> ====================================================================
> The moment I start Emacs, I get the error message
> 
> Error running timer 'blink-cursor-start': (wrong-type-argument listp
> 0.5)
> 
> It then refuses all keyboard input; for example C-x d gets the error
> message Wrong type argument: listp 10
> ====================================================================
> 
> I managed to run Emacs without the suggested -Q just enough to open the
> messages buffer with the mouse and grab the contents. Then quit and run
> again with -Q and paste the message contents into a file to save
> it. This is what it says:
> 
> Loading 00debian-vars...done
> Loading /etc/emacs/site-start.d/50asymptote.el (source)...done
> Loading /etc/emacs/site-start.d/50autoconf.el (source)...done
> Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...
> Loading debian-ispell...
> Loading /var/cache/dictionaries-common/emacsen-ispell-default.el 
> (source)...done
> Loading debian-ispell...done
> Loading /var/cache/dictionaries-common/emacsen-ispell-dicts.el 
> (source)...done
> Loading /etc/emacs/site-start.d/50dictionaries-common.el (source)...done
> Loading /etc/emacs/site-start.d/50latex-cjk-common.el (source)...
> Loading cjk-enc...done
> Loading /etc/emacs/site-start.d/50latex-cjk-common.el (source)...done
> Loading /etc/emacs/site-start.d/50latex-cjk-thai.el (source)...done
> Loading /etc/emacs/site-start.d/50texlive-lang-english.el (source)...done
> For information about GNU Emacs and the GNU system, type C-h C-a.
> setq: Wrong type argument: listp, 10
> Error running timer ‘blink-cursor-start’: (wrong-type-argument listp 
> 0.5) [2 times]
> setq: Wrong type argument: listp, 0.7
> Error running timer ‘blink-cursor-start’: (wrong-type-argument listp 
> 0.5) [5 times]
> Mark set
> Error running timer ‘blink-cursor-start’: (wrong-type-argument listp 0.5)
> setq: Wrong type argument: listp, 0.7 [2 times]
> Error running timer ‘blink-cursor-start’: (wrong-type-argument listp 0.5)
> setq: Wrong type argument: listp, 0.7
> Error running timer ‘blink-cursor-start’: (wrong-type-argument listp 
> 0.5) [4 times]

Please try "emacs -q" (lower-case "q", not "Q").  If the problem
happens with -q as well, then its cause is somewhere in all those
site-start.d/50*.el files Emacs loads at startup -- those come from
your system's Emacs distro.

If the problem doesn't happen with -q, then its cause is in your init
file, ~/.emacs.