fixes #284, fix regression

lib/models/resources/ResourceRequest.class.php

@@ -1198,9 +1198,12 @@ class ResourceRequest extends SimpleORMap implements PrivacyObject, Studip\Calen
         $intervals = $this->getTimeIntervals(false, true);
         foreach ($intervals as $interval) {
             $room = '';
-            $date = call_user_func([$interval['range'], 'find'], $interval['range_id']);
-            if ($room_obj = Room::find($date->room_booking->resource_id)) {
-                $room = $room_obj->name;
+
+            if ($interval['range'] == 'CourseDate') {
+                $date = call_user_func([$interval['range'], 'find'], $interval['range_id']);
+                if ($room_obj = Room::find($date->room_booking->resource_id)) {
+                    $room = $room_obj->name;
+                }
             }
 
             $same_day = (date('Ymd', $interval['begin'])