patch 8.2.3282: Vim9: error about using -complete without -nargs is confusing

Problem:    Vim9: error about using -complete without -nargs is confusing.
Solution:   Change the wording.
diff --git a/src/usercmd.c b/src/usercmd.c
index 41f8e04..bc0b870 100644
--- a/src/usercmd.c
+++ b/src/usercmd.c
@@ -1077,10 +1077,11 @@
 	// Some plugins rely on silently ignoring the mistake, only make this
 	// an error in Vim9 script.
 	if (in_vim9script())
-	    emsg(_(e_complete_used_without_nargs));
+	    emsg(_(e_complete_used_without_allowing_arguments));
 	else
 	    give_warning_with_source(
-		       (char_u *)_(e_complete_used_without_nargs), TRUE, TRUE);
+		       (char_u *)_(e_complete_used_without_allowing_arguments),
+								   TRUE, TRUE);
     }
     else
     {