feat: return a empty dict when get_last_indexed returns nothing

flowrun/storage/elasticsearch.py

@@ -33,7 +33,7 @@ def get_last_indexed(self, org):
             )["hits"]["hits"][0]["_source"]
         except (AttributeError, TypeError, IndexError) as err:
             print("[-] <Warning> Elasticsearch Get error: ", type(err), err)
-            return None
+            return {}
         return es_flow_run
 
     def get_last_indexed_timestamp(self, org):