diff --git a/langgraph/graph/state.py b/langgraph/graph/state.py
index 45fb5ec65..1a3f5530e 100644
--- a/langgraph/graph/state.py
+++ b/langgraph/graph/state.py
@@ -122,3 +122,4 @@ def _is_field_binop(typ: Type[Any]) -> Optional[BinaryOperatorAggregate]:
                 ]
             ):
                 return BinaryOperatorAggregate(typ, meta[0])
+    return None
diff --git a/langgraph/pregel/read.py b/langgraph/pregel/read.py
index 0d566791f..78129b5b0 100644
--- a/langgraph/pregel/read.py
+++ b/langgraph/pregel/read.py
@@ -104,7 +104,7 @@ class ChannelInvoke(RunnableBindingBase):
             when=when,
             bound=bound or default_bound,
             kwargs=kwargs or {},
-            config=merge_configs(config, {"tags": tags}),
+            config=merge_configs(config, {"tags": tags or []}),
             **other_kwargs,
         )
 
diff --git a/tests/test_pregel.py b/tests/test_pregel.py
index fd4a986b5..0ad0b5752 100644
--- a/tests/test_pregel.py
+++ b/tests/test_pregel.py
@@ -811,7 +811,7 @@ def test_conditional_graph_state() -> None:
         ]
     )
 
-    def agent_parser(input: str) -> Union[AgentAction, AgentFinish]:
+    def agent_parser(input: str) -> dict[str, Union[AgentAction, AgentFinish]]:
         if input.startswith("finish"):
             _, answer = input.split(":")
             return {
diff --git a/tests/test_pregel_async.py b/tests/test_pregel_async.py
index 6799bdd73..1b162cbb8 100644
--- a/tests/test_pregel_async.py
+++ b/tests/test_pregel_async.py
@@ -865,7 +865,7 @@ async def test_conditional_graph_state() -> None:
         ]
     )
 
-    def agent_parser(input: str) -> Union[AgentAction, AgentFinish]:
+    def agent_parser(input: str) -> dict[str, Union[AgentAction, AgentFinish]]:
         if input.startswith("finish"):
             _, answer = input.split(":")
             return {