According to https://ctan.org/pkg/grffile, since 2019-11-08, grffile is a stub
that just loads graphicx, part of texlive-latex-graphics, part of texlive-base.
My system (Guix) doesn't have a package for grffile, so I can't generate a
PDF, which is silly because it's a stub anyway.
Suggest fixing by removing \usepackage{grffile} in LaTeX export.
A caveat: some distributions seem to still package an old TeXLive full distribution,
going by Guix which provides a three-gigabyte "texlive" package from
2019-04-10. I'm not sure what sort of deprecation time we allow.