added additional filter

islandora.module

@@ -2175,6 +2175,7 @@ function islandora_islandora_get_breadcrumb_query_predicates(AbstractObject $obj
  * Implements hook_islandora_overview_object().
  */
 function islandora_islandora_overview_object(AbstractObject $object) {
+  if (is_object($object)) {
     $cmodels = $object->models;
     $rows = array();
     foreach ($cmodels as $cmodel) {
@@ -2190,3 +2191,4 @@ function islandora_islandora_overview_object(AbstractObject $object) {
       'empty' => t('No Islandora content model associated with this object.')));
     return array('cmodels' => $table);
   }
+}