Fixed search documents to coalesce empty parent entities.

docs/associated-tags.sql

@@ -2,4 +2,6 @@ SELECT tags.name FROM actors
 LEFT JOIN releases_actors ON releases_actors.actor_id = actors.id
 LEFT JOIN releases_tags ON releases_tags.release_id = releases_actors.release_id
 LEFT JOIN tags ON tags.id = releases_tags.tag_id
-WHERE actors.slug = 'vina-sky';
+WHERE actors.slug = 'vina-sky'
+GROUP BY tags.id
+ORDER BY tags.name;