Failed to run langserve/examples/chat_with_persistence

[yingflower]

I got an exception like this when run the server:
Traceback (most recent call last):
File "/workspace/llm/langserve/examples/chat_with_persistence/server.py", line 105, in
add_routes(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/langserve/server.py", line 443, in add_routes
api_handler = APIHandler(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/langserve/api_handler.py", line 671, in init
output_type_ = _resolve_model(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/langserve/api_handler.py", line 338, in resolve_model
hash = model.schema_json()
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/main.py", line 675, in schema_json
cls.schema(by_alias=by_alias, ref_template=ref_template), default=pydantic_encoder, **dumps_kwargs
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/main.py", line 664, in schema
s = model_schema(cls, by_alias=by_alias, ref_template=ref_template)
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/schema.py", line 188, in model_schema
m_schema, m_definitions, nested_models = model_process_schema(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/schema.py", line 581, in model_process_schema
m_schema, m_definitions, nested_models = model_type_schema(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/schema.py", line 622, in model_type_schema
f_schema, f_definitions, f_nested_models = field_schema(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/schema.py", line 255, in field_schema
f_schema, f_definitions, f_nested_models = field_type_schema(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/schema.py", line 527, in field_type_schema
f_schema, f_definitions, f_nested_models = field_singleton_schema(
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/site-packages/pydantic/v1/schema.py", line 926, in field_singleton_schema
if issubclass(field_type, BaseModel):
File "/home/feirong.zfr/anaconda3/envs/lc/lib/python3.10/abc.py", line 123, in subclasscheck
return _abc_subclasscheck(cls, subclass)
TypeError: issubclass() arg 1 must be a class

My langchain versions is as follows:
langchain 0.2.16
langchain-anthropic 0.1.23
langchain-community 0.2.16
langchain-core 0.2.38
langchain-openai 0.1.23
langchain-text-splitters 0.2.4
langserve 0.2.3

[eyurtsev]

duplicate of #742