Make sgml-validate not bug out from buffers not visiting a file

* lisp/textmodes/sgml-mode.el (sgml-validate): Don't bug out when
running from a buffer that's not visiting a file (bug#22906).

1 files changed, 3 insertions, 4 deletions

diff --git a/lisp/textmodes/sgml-mode.el b/lisp/textmodes/sgml-mode.el
index e0ef786953e..f3d8695e248 100644
--- a/lisp/textmodes/sgml-mode.el
+++ b/lisp/textmodes/sgml-mode.el
@@ -1188,10 +1188,9 @@ and move to the line in the SGML document that caused it."
                       (or sgml-saved-validate-command
                           (concat sgml-validate-command
                                   " "
-                                  (shell-quote-argument
-                                   (let ((name (buffer-file-name)))
-                                     (and name
-                                          (file-name-nondirectory name)))))))))
+                                  (when-let ((name (buffer-file-name)))
+                                    (shell-quote-argument
+                                     (file-name-nondirectory name))))))))
   (setq sgml-saved-validate-command command)
   (save-some-buffers (not compilation-ask-about-save) nil)
   (compilation-start command))