(fill-context-prefix): Don't crash if RESULT is nil when AT-SECOND is t.

diff --git a/lisp/textmodes/fill.el b/lisp/textmodes/fill.el
index 552bd4fb68cedbf623e5d20cd23252cb8f8cd9f8..c3628be99f88ef1f4c3896e46bb1646cf261b835 100644 (file)
--- a/lisp/textmodes/fill.el
+++ b/lisp/textmodes/fill.el
@@ -200,10 +200,11 @@ act as a paragraph-separator."
        (if at-second
            ;; If we get a fill prefix from the second line,
            ;; make sure it's on the first line too.
-           (save-excursion
-             (forward-line -1)
-             (if (looking-at (regexp-quote result))
-                 result))
+           (and result
+                (save-excursion
+                  (forward-line -1)
+                  (if (looking-at (regexp-quote result))
+                      result)))
          ;; If we get a fill prefix from a one-line paragraph,
          ;; maybe change it to whitespace,
          ;; and check that it isn't a paragraph starter.