Skip bad pending sends

libs/langgraph/langgraph/pregel/__init__.py

@@ -1816,6 +1816,9 @@ def _prepare_next_tasks(
     tasks: Union[list[PregelTaskDescription], list[PregelExecutableTask]] = []
     # Consume pending packets
     for packet in checkpoint["pending_sends"]:
+        if not isinstance(packet, Send):
+            logger.warn(f"Ignoring invalid packet type {type(packet)} in pending sends")
+            continue
         if for_execution:
             if node := processes[packet.node].get_node():
                 writes = deque()