comment follow-up

src/do_name.c

@@ -1488,7 +1488,9 @@ do_oname(struct obj *obj)
            a valid artifact name */
         u.uconduct.literate++;
     } else if (obj->otyp == objtyp) {
+        /* artifact_name() always returns non-Null when it sets objtyp */
         assert(aname != 0);
+
         /* artifact_name() found a match and restrict_name() didn't reject
            it; since 'obj' is the right type, naming will change it into an
            artifact so use canonical capitalization (Sting or Orcrist) */