bug#68940: 29.2; Random crashes in face for char / font

[Robert Vojta]

> Just to clarify: if you start "emacs -Q", then evaluate
>
>   M-: (setq org-ellipsis (if (char-displayable-p ?⏷) "\t⏷" nil)) RET
>
> then visit some Org file and try toggling visibility (so that
> org-ellipsis is used), does it crash?

No, this one does not crash Emacs. If I get after the launch Emacs
phase, it works as expected, never crashed. An interesting fact - Emacs
launched with "--debug-init" & this ellipsis never crashed too.

 - "emacs -Q" = no crash, expected
 - "(setq org-ellipsis ...)" in my init.el
   - "emacs --debug-init" = no crash too, never crashed
   - "emacs" - crash in 80%, once running, never crashed

> If not, something else in your customizations "helps" the bug to
> happen, perhaps some font-related settings?

I'm using PragmataPro Mono font. I've tried another fonts, e.g. Menlo,
... and it is crashing w/ them too. It seems that it is not font
related.

I know that it does not crash with "emacs -Q", crashes w/ my config, and
I also know which line is causing it. Right now I'm trying to come up w/
a minimal init.el that can reproduce this issue.

Thanks.