bug#30112: 27.0.50; bibtex-mode timer and redisplay errors

[Lars Ingebrigtsen]

"Basil L. Contovounesios" <contovob@tcd.ie> writes:

> Enabling debug on error does not provide much more context:
>
>   Debugger entered--Lisp error:
>       (wrong-type-argument number-or-marker-p nil)
>     bibtex-parse-keys(t)
>     bibtex-parse-buffers-stealthily()
>     apply(bibtex-parse-buffers-stealthily nil)
>     timer-event-handler
>       ([t 0 4 0 t bibtex-parse-buffers-stealthily nil idle 0])

I've now added a sanity check to bibtex-parse-keys to abort in these
situations to Emacs 27.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no