Fixed issue where we were attempting to save/update phantom post/page when on nav-menu admin panel and save button was pressed. This triggered a "Warning: Creating default object from empty value in /home/{site root}/public_html/wp-content/plugins/wp-post-to-pdf-enhanced/wp-post-to-pdf-enhanced.php on line ###" which could only happen if we were trying to update a cached pdf. This is an ugly workaround.

git-svn-id: https://plugins.svn.wordpress.org/wp-post-to-pdf-enhanced/trunk@871661 b8457f37-d9ea-0310-8a92-e5e31aec5664