No -r activity?
    On Saturday, January 18, 2025 at 12:30:01 AM EST, Jim Meyering <jim@meyering.net> wrote:   

 On Fri, Jan 17, 2025 at 10:35 AM David G. Pickett <dgpickett@aol.com> wrote:
> Should both -r and file names raise an error?
>
> $ grep -r xxx yyy zzz
> grep: yyy: No such file or directory
> grep: zzz: No such file or directory

That is expected behavior.
In that case, you've made a legitimate request to search recursively
for "xxx" in yyy and zzz.
It would probably elicit no diagnostic if you had files or directories
named yyy and zzz.