Yes, it is not an error .

My mkiv is on a linux box, and it's made only
from pragma last_core_files (setuplinux.zip) + last_stables_zip_iles + last_luatex+last_metapost .
So, it's a way to signal that there is a reference to a font that in not in these files.
Of course, I can download fonts and update, (I have done it for tex-gyre only opentype)
but i want  a clean, clear and minimal mviv system .