[BUG] org-indent-line edge case in empty Org mode buffer [9.8-pre (release_9.7.6-107-gf21415 @ /home/jschmidt/work/org-mode/lisp/)]

[Jens Schmidt]

The following sequence of commands:

  make vanilla
  M-x org-mode RET
  M-x erase-buffer RET SPC
  M-: (setq org-adapt-indentation 'headline-data)
  M-x org-indent-line RET

results in:

  Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
    org-indent-line()
    funcall-interactively(org-indent-line)
    command-execute(org-indent-line record)
    execute-extended-command(nil "org-indent-line" "org-indent-li")
    funcall-interactively(execute-extended-command nil "org-indent-line" 
"org-indent-li")
    command-execute(execute-extended-command)

`org-indent-line' probably should test ELEMENT on nil-ness, but I'm not
sure where exactly.

Emacs  : GNU Emacs 28.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.38, 
cairo version 1.16.0)
 of 2024-06-25, modified by Debian
Package: Org mode version 9.8-pre (release_9.7.6-107-gf21415 @ 
/home/jschmidt/work/org-mode/lisp/)