bug#64024: 29.0.91; `emoji-insert` shows me confusing empty lists

[Gregory Heytings]

> > % src/emacs -Q
> > M-x emoji-insert RET
> > s s
> >
> > I expect at this point to see a list of "smiling Smiley" emojis 
> > displayed in the small bottom window, but instead that window is empty 
> > (there's just a one-pixel-thick line about one-char wide at the very 
> > top-left) and it sits there.
>
> I cannot reproduce this, neither in the 29.0.91 pretest nor in the 
> current emacs-29 branch.  I get the behavior you expected: a small 
> window at the bottom of the frame showing some smileys.

FWIW, I can easily reproduce this by removing the fonts-noto-color-emoji 
package.

Perhaps the emoji-* commands (C-x 8 e [eilrs]) should simply error out 
when (list-fonts (font-spec :script 'emoji)) is nil?