Parameter view_mode missing

Closes #3507901

src/Plugin/views/field/SearchApiFlag.php

@@ -33,6 +33,7 @@ class SearchApiFlag extends FieldPluginBase implements FieldHandlerInterface {
           $entity_type_id,
           $entity_id,
           $flag_id,
+          'default',
         ],
       ],
       '#create_placeholder' => FALSE,