bug#67815: Commit dcd755dabcf9ef95d6d0534c11c668f44c6f89c2 kills org-beamer-export-to-pdf

[Eli Zaretskii]

> From: Pedro Andres Aranda Gutierrez <paaguti@gmail.com>
> Date: Wed, 13 Dec 2023 20:40:05 +0100
> 
> command:
> 
> emacs -Q -l export-beamer.el --batch flat.org --eval 
> '(org-beamer-export-to-pdf)'
> error produced
> 
> File mode specification error: (error Invalid face box :line-width 1 :color 
> grey40)

In fact, just loading ox-beamer.el produces the same error.

> Previous commit (a91185211924f65adf7c1376b7f2d710099a5903) produces the PDF 
> file

It's a bug in org-beamer.el.  It defines that face incorrectly:

  (defface org-beamer-tag '((t (:box (:line-width 1 :color grey40))))
                                                           ^^^^^^
"grey40" should be a string, not a symbol.

This bug is already fixed in Org on the emacs-29 release branch, so it
will be fixed soon on master as well, when we next merge emacs-29 onto
master.

I'm therefore closing this bug.

P.S. In general, whenever any errors pop up due to the above commit,
it is almost certainly a bug in the face definition (which previously
went unnoticed), so people should first and foremost look at the face
definition, because more often than not, there's a real bug there.