fix DFL update handler bad processing of advanced round updates received

Author: AlejandroAvilesSerrano

nebula/core/aggregation/updatehandlers/dflupdatehandler.py

@@ -88,11 +88,13 @@ async def round_expected_updates(self, federation_nodes: set):
     async def _check_updates_already_received(self):
         for se in self._sources_expected:
             (last_updt, node_storage) = self._updates_storage[se]
-            if len(node_storage) and last_updt != node_storage[-1]:
-                    logging.info(
-                        f"Update already received from source: {se} | ({len(self._sources_received)}/{len(self._sources_expected)}) Updates received"
-                    )
-                    self._sources_received.add(se)
+            if len(node_storage):
+                try:
+                    if (last_updt and node_storage[-1] and last_updt != node_storage[-1]) or (node_storage[-1] and not last_updt):
+                        self._sources_received.add(se)
+                        logging.info(f"Update already received from source: {se} | ({len(self._sources_received)}/{len(self._sources_expected)}) Updates received")
+                except:
+                    logging.error(f"ERROR: source expected: {se} | last_update None: {(True if not last_updt else False)}, last update storaged None: {(True if not node_storage[-1] else False)}")
 
     async def storage_update(self, updt_received_event: UpdateReceivedEvent):
         time_received = time.time()