I believe there may be a bug in fontconfig or the setup thereof - please
see:
https://bugs.freedesktop.org/show_bug.cgi?id=4236
Specifically, the fonts.conf file attempts to include /etc/fonts/conf.d,
but the parser does not understand how to include a directory, and
instead attempts to open the directory as a file.
Directly including the files within conf.d does not work either, and
throws other errors.