[BUG] Texinfo: Error when exporting source block with no language

[8dcc]

Hello, when trying to export the following Org file:

    #+begin_src
    Hello, world.
    #+end_src

To texinfo using `org-texinfo-export-to-texinfo', I get the following
error:

    Debugger entered--Lisp error: (wrong-type-argument stringp nil)
      org-texinfo-src-block((src-block (:language nil <snip>)))
      org-export-data((src-block (:language nil <snip>)))

However, if I change contents of the Org file to this, even if it's a
non-existing language, it works:

    #+begin_src foobar
    Hello, world.
    #+end_src

And produces:

    <...>
    @example
    Hello, world.
    @end example
    <...>

I am using Org mode version 9.6.15 in GNU Emacs 29.4.

Thanks.