Fixed datastream error handling

includes/datastream.inc

@@ -19,10 +19,6 @@ function islandora_datastream_as_attachment($object_id, $dsid) {
   try {
     $restConnection = new RestConnection($user);
     $fedora_object = new FedoraObject($object_id, $restConnection->repository);
-  } catch (Exception $e) {
-    drupal_set_message(t('Error getting Islanndora datastream $d for object %s', array('%s' => $object_id, '%d' => $dsid)), 'error');
-    return"";
-  }
     header('Content-type: ' . $fedora_object[$dsid]->mimetype);
     if($fedora_object[$dsid]->controlGroup == 'M' || $fedora_object[$dsid]->controlGroup == 'X') {
       header('Content-length: ' . $fedora_object[$dsid]->size);
@@ -34,6 +30,9 @@ function islandora_datastream_as_attachment($object_id, $dsid) {
     }
     print($fedora_object[$dsid]->content);
     exit();
+  } catch (Exception $e) {
+    return drupal_not_found();;
+  }
 }
 
 function islandora_get_datastream_parents($islandora_object) {