(disable-command): Reject invalid commands.

diff --git a/lisp/novice.el b/lisp/novice.el
index 2353edc5719eb1bc013e9ebd3c6786226b28c671..972d0737649d37e54d09247d064d341e81ddda62 100644 (file)
--- a/lisp/novice.el
+++ b/lisp/novice.el
@@ -108,6 +108,8 @@ to future sessions."
 The user's .emacs file is altered so that this will apply
 to future sessions."
   (interactive "CDisable command: ")
+  (if (not (commandp command))
+      (error "Invalid command name `%s'" command))
   (put command 'disabled t)
   (save-excursion
    (set-buffer (find-file-noselect