Ensure empty name is NULL in name_en

layers/transportation_name/layer.sql

@@ -6,7 +6,7 @@ CREATE OR REPLACE FUNCTION layer_transportation_name(bbox geometry, zoom_level i
 RETURNS TABLE(osm_id bigint, geometry geometry, name text, name_en text, ref text, ref_length int, network text, class text) AS $$
     SELECT osm_id, geometry,
       NULLIF(name, '') AS name,
-      COALESCE(NULLIF(name_en, ''), name) AS name_en,
+      COALESCE(NULLIF(name_en, ''), NULLIF(name, '')) AS name_en,
       NULLIF(ref, ''), NULLIF(LENGTH(ref), 0) AS ref_length,
       --TODO: The road network of the road is not yet implemented
       NULL::text AS network,