catch empty results

MANIFEST.in

-include rules/gem_occupancy/data/*.csv
+include rabotnikobm/rules/gem_occupancy/data/*.csv
 include LICENSE

rabotnikobm/rules/gem_occupancy/get_building_occupancy.py

@@ -130,6 +130,10 @@ class GetBuildingOccupancy(Rule):
             f"SELECT tags FROM osm_building_relations WHERE osm_id={building_id} AND index=0"
         )
 
+        logger.debug(f"working on tags: {tags}")
+        if not tags:
+            return
+
         # Mapping to GEM taxonomy strings
         occupancies = []
         for mapper in self.mappers: