Display error message when attempting to edit post or page IDs that do not...

Display error message when attempting to edit post or page IDs that do not exist.  Props Viper007Bond. fixes #4737

git-svn-id: http://svn.automattic.com/wordpress/trunk@5875 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/page.php

@@ -45,6 +45,8 @@ case 'edit':
 	$page_ID = $post_ID = $p = (int) $_GET['post'];
 	$post = get_post_to_edit($page_ID);
 
+	if ( empty($post->ID) ) wp_die( __("You attempted to edit a page that doesn't exist. Perhaps it was deleted?") );
+
 	if ( 'post' == $post->post_type ) {
 		wp_redirect("post.php?action=edit&post=$post_ID");
 		exit();

wp-admin/post.php

@@ -48,6 +48,8 @@ case 'edit':
 	$post_ID = $p = (int) $_GET['post'];
 	$post = get_post($post_ID);
 
+	if ( empty($post->ID) ) wp_die( __("You attempted to edit a post that doesn't exist. Perhaps it was deleted?") );
+
 	if ( 'page' == $post->post_type ) {
 		wp_redirect("page.php?action=edit&post=$post_ID");
 		exit();