Index: flag.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/flag/Attic/flag.module,v
retrieving revision 1.11.2.72
diff -u -p -r1.11.2.72 flag.module
--- flag.module	15 Jun 2009 20:05:42 -0000	1.11.2.72
+++ flag.module	29 Jun 2009 05:13:27 -0000
@@ -673,12 +673,20 @@ function template_preprocess_flag(&$vari
 
   // Generate the link URL.
   $link_types = flag_get_link_types();
+  if (!isset($link_types[$flag->link_type])) {
+    $msg = t('Flag "@flag_name" has flag link type "@flag_link_type" which no longer exists.', array('@flag_name' => $flag->name, '@flag_link_type' => $flag->link_type));
+    watchdog('warning', $msg);
+    if (user_access('administer flags')) {
+      drupal_set_message ($msg, 'warning');
+    }
+    return;
+  }
   $link_type_module = $link_types[$flag->link_type]['module'];
   $link = module_invoke($link_type_module, 'flag_link', $flag, $action, $content_id);
   if (isset($link['title']) && empty($link['html'])) {
     $link['title'] = check_plain($link['title']);
   }
-
+  
   if ($flag->link_type == 'toggle' && $first_time) {
     $variables['setup'] = $first_time;
     $first_time = FALSE;