[BUG] 30.1; regression to 29.4 org-mode wrong-type-argument number-or-marker-p nil [9.7.11 (release_9.7.11 @ /usr/share/emacs/30.1/lisp/org/)]

[Evgeniy Dushistov via "General discussions about Org-mode." <emacs-orgmode@gnu.org>]

If I run "emacs -Q" and then eval such config:

```
(setq use-package-verbose t)

(use-package org
  :commands (org-capture org-agenda)
  :hook (org-mode . flyspell-mode)
  :config
  (message "Running :config of org-mode")
  (setq org-startup-folded t)
  (setq org-edit-src-content-indentation 0)
  (org-babel-do-load-languages
   'org-babel-load-languages
   '((python . t)))
  )

(with-eval-after-load 'org
  (require 'org-tempo))
```

run M-x toggle-debug-on-error
and then open such org file:

```
* How watch variable
#+begin_src gdb
watch var
#+end_src
removing watch
#+begin_src gdb
(gdb) info watchpoint
Num     Type           Disp Enb Address            What
11      hw watchpoint  keep y                      *0x7fffffffd1a0
12      watchpoint     keep y                      finfo
	breakpoint already hit 22 times
(gdb) del 11
(gdb) del 12
#+end_src
```

I get such backtracke:

```
Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  org-src-font-lock-fontify-block(#("gdb" 0 3 (fontified t)) 88 350)
  org-fontify-meta-lines-and-blocks-1(360)
  org-fontify-meta-lines-and-blocks(360)
  font-lock-fontify-keywords-region(1 360 nil)
  font-lock-default-fontify-region(1 360 nil)
  font-lock-fontify-region(1 360)
  #f(compiled-function (fun) #<bytecode 0x1bab259db1315c3f>)(font-lock-fontify-region)
  jit-lock--run-functions(1 360)
  jit-lock-fontify-now(1 360)
  jit-lock-function(1)
  redisplay_internal\ \(C\ function\)()
```

With emacs-29.4 I do not get any errors.


Emacs  : GNU Emacs 30.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.48, cairo version 1.18.2)
Package: Org mode version 9.7.11 (release_9.7.11 @ /usr/share/emacs/30.1/lisp/org/)

current state:
==============
(setq
 org-yank-image-file-name-function 'org-yank-image-autogen-filename
 org-persist-before-write-hook '(org-element--cache-persist-before-write)
 org-babel-tangle-lang-exts '(("python" . "py") ("emacs-lisp" . "el") ("elisp" . "el"))
 org-speed-command-hook '(org-speed-command-activate org-babel-speed-command-activate)
 org-persist-after-read-hook '(org-element--cache-persist-after-read)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-mode-hook '(org-tempo-setup
		 #[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-fold-show-all append local] 5]
		 #[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-babel-show-result-all append local] 5]
		 org-babel-result-hide-spec org-babel-hide-all-hashes flyspell-mode)
 org-confirm-shell-link-function 'yes-or-no-p
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-occur-hook '(org-first-headline-recenter)
 org-edit-src-content-indentation 0
 org-bibtex-headline-format-function 'org-bibtex-headline-format-default
 org-link-parameters '(("attachment" :follow org-attach-follow :complete org-attach-complete-link)
		       ("id" :follow org-id-open :store org-id-store-link-maybe)
		       ("eww" :follow org-eww-open :store org-eww-store-link)
		       ("rmail" :follow org-rmail-open :store org-rmail-store-link)
		       ("mhe" :follow org-mhe-open :store org-mhe-store-link)
		       ("irc" :follow org-irc-visit :store org-irc-store-link :export org-irc-export)
		       ("info" :follow org-info-open :export org-info-export :store org-info-store-link :insert-description
			org-info-description-as-command)
		       ("gnus" :follow org-gnus-open :store org-gnus-store-link)
		       ("docview" :follow org-docview-open :export org-docview-export :store org-docview-store-link)
		       ("bibtex" :follow org-bibtex-open :store org-bibtex-store-link)
		       ("bbdb" :follow org-bbdb-open :export org-bbdb-export :complete org-bbdb-complete-link :store
			org-bbdb-store-link)
		       ("w3m" :store org-w3m-store-link) ("doi" :follow org-link-doi-open :export org-link-doi-export)
		       ("file+sys") ("file+emacs") ("shell" :follow org-link--open-shell)
		       ("news" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["news" browse-url ":"] 6 "\n\n(fn URL ARG)"])
		       ("mailto" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["mailto" browse-url ":"] 6 "\n\n(fn URL ARG)"])
		       ("https" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["https" browse-url ":"] 6 "\n\n(fn URL ARG)"])
		       ("http" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["http" browse-url ":"] 6 "\n\n(fn URL ARG)"])
		       ("ftp" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["ftp" browse-url ":"] 6 "\n\n(fn URL ARG)"])
		       ("help" :follow org-link--open-help :store org-link--store-help)
		       ("file" :complete org-link-complete-file) ("elisp" :follow org-link--open-elisp))
 org-persist-directory "/tmp/org-persist-2wxdWl"
 org-cycle-tab-first-hook '(org-babel-hide-result-toggle-maybe org-babel-header-arg-expand)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-tab-before-tab-emulation-hook '(org-tempo-complete-tag)
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe org-babel-header-arg-expand)
 org-sort-function 'string-collate-lessp
 org--warnings nil
 org-startup-folded t
 org-babel-pre-tangle-hook '(save-buffer)
 org-export-before-parsing-hook '(org-attach-expand-links)
 org-link-shell-confirm-function 'yes-or-no-p
 org-fold-core-isearch-open-function 'org-fold-core--isearch-reveal
 outline-isearch-open-invisible-function 'outline-isearch-open-invisible
 org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer)
 org-babel-load-languages '((python . t))
 org-agenda-loop-over-headlines-in-active-region nil
 org-link-elisp-confirm-function 'yes-or-no-p
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-show-empty-lines
		  org-cycle-optimize-window-after-visibility-change org-cycle-display-inline-images)
 org-persist-before-read-hook '(org-element--cache-persist-before-read)
 )

-- 
/Evgeniy