Fix Error: TypeError: Object of type object is not JSON serializable

[Huarong]

Make json dump more robust. Support object type.
Fix the error like this, which occur in using langraph.

  File "/Users/huohuarong/.pyenv/versions/3.11.2/lib/python3.11/json/encoder.py", line 258, in iterencode
    return _iterencode(o, 0)
           │           └ {'id': 'd4b690a2-78b9-4bc3-bda0-98e5e6c62366', 'type': 'span-update', 'body': {'output': <object object at 0x120809540>, 'id'...
           └ <_json.Encoder object at 0x1253fa080>
  File "/Users/huohuarong/llm/doctorgpt/.venv/lib/python3.11/site-packages/langfuse/serializer.py", line 55, in default
    return JSONEncoder.default(self, obj)
           │           │       │     └ <object object at 0x120809540>
           │           │       └ <langfuse.serializer.EventSerializer object at 0x1253b3050>
           │           └ <function JSONEncoder.default at 0x101e6d580>
           └ <class 'json.encoder.JSONEncoder'>
  File "/Users/huohuarong/.pyenv/versions/3.11.2/lib/python3.11/json/encoder.py", line 180, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '

TypeError: Object of type object is not JSON serializable

[CLAassistant]

All committers have signed the CLA.

[maxdeichmann]

@Huarong thanks for the change. Unfortunately, the string representation of an object would not really be helpful, as our users would see the object name and the memory address in the UI.
Do you know which type of object langraph is trying to send here? Do you mind sharing your graph with us?