fixed php warning

sites/all/modules/gui/materiobasemod/materio_showroom.module

@@ -331,10 +331,13 @@ function _materio_showroom_alter_location_field_form(&$form, &$form_state, $form
       // get user own term for current vocabulary (if any)
       if(isset($user_termref_field_instances[$voc->machine_name])){
         $user_field_name = $user_termref_field_instances[$voc->machine_name];
-        foreach (field_get_items('user', $user, $user_field_name) as $key => $value) {
-          $user_showrooms[] = $value['tid'];
+        $field_items = field_get_items('user', $user, $user_field_name);
+        if (is_array($field_items) || $field_items instanceof Traversable){
+          foreach ($field_items as $key => $value) {
+            $user_showrooms[] = $value['tid'];
+          }
+          // dsm($user_showrooms, "user_showrooms");
         }
-        // dsm($user_showrooms, "user_showrooms");
       }
 
       // get already recorded values