Bugfix: Protect string-match against nil string.

Bugfix: Protect string-match against nil string.

Friedrich Delgado Friedrichs writes:

A while ago I had this problem:
org-infojs-handle-options: Wrong type argument: stringp, nil

I wonder if my patch ever reached the mailing list, or if it
was overlooked because it was too close to christmas:

Friedrich Delgado Friedrichs schrieb:
From 0fef25f56c837ae9f434449c6f30268e0474f7ab Mon Sep 17 00:00:00 2001
From: Friedrich Delgado Friedrichs <delgado@dfn-cert.de>
Date: Tue, 23 Dec 2008 12:10:42 +0100
Subject: [PATCH] fix string-match against nil when no in-file options are set for jsinfo

---
lisp/org-jsinfo.el |    3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/lisp/org-jsinfo.el b/lisp/org-jsinfo.el
index 8f2d7e8..19faa9e 100644
--- a/lisp/org-jsinfo.el
+++ b/lisp/org-jsinfo.el
@@ -140,7 +140,8 @@ Option settings will replace the %MANAGER-OPTIONS cookie."
            default (cdr (assoc opt org-infojs-options)))
      (and (symbolp default) (not (memq default '(t nil)))
           (setq default (plist-get exp-plist default)))
-      (if (string-match (format " %s:\\(\\S-+\\)" opt) v)
+      (if (and v
+               (string-match (format " %s:\\(\\S-+\\)" opt) v))
          (setq val (match-string 1 v))
        (setq val default))
      (cond