[Bug]: Exception when deleting messages

[frankxu2004]

Is there an existing issue for the same bug?

• I have checked the troubleshooting document at https://opendevin.github.io/OpenDevin/modules/usage/troubleshooting
• I have checked the existing issues.

Describe the bug

Randomly if the session restarts or disconnects, delete_messages will be called and the following appears in the logs:

INFO:     127.0.0.1:36072 - "GET /api/agents HTTP/1.1" 200 OK
INFO:     127.0.0.1:36086 - "DELETE /api/messages HTTP/1.1" 200 OK
13:19:45 - opendevin:INFO: msg_stack.py:95 - Deleting messages...
ERROR:asyncio:Task exception was never retrieved
future: <Task finished name='Task-18' coro=<MessageStack._del_messages() done, defined at /projects/ogma3/fangzhex/OpenDevin/opendevin/server/session/msg_stack.py:94> exception=TypeError('Object of type Message is not JSON serializable')>
Traceback (most recent call last):
  File "/projects/ogma3/fangzhex/OpenDevin/opendevin/server/session/msg_stack.py", line 107, in _del_messages
    json.dump(new_data, file)
  File "/home/fangzhex/miniconda3/lib/python3.11/json/__init__.py", line 179, in dump
    for chunk in iterable:
  File "/home/fangzhex/miniconda3/lib/python3.11/json/encoder.py", line 432, in _iterencode
    yield from _iterencode_dict(o, _current_indent_level)
  File "/home/fangzhex/miniconda3/lib/python3.11/json/encoder.py", line 406, in _iterencode_dict
    yield from chunks
  File "/home/fangzhex/miniconda3/lib/python3.11/json/encoder.py", line 326, in _iterencode_list
    yield from chunks
  File "/home/fangzhex/miniconda3/lib/python3.11/json/encoder.py", line 439, in _iterencode
    o = _default(o)
        ^^^^^^^^^^^
  File "/home/fangzhex/miniconda3/lib/python3.11/json/encoder.py", line 180, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type Message is not JSON serializable

Current Version

main branch

Installation and Configuration

make run

Model and Agent

No response

Reproduction Steps

No response

Logs, Errors, Screenshots, and Additional Context

No response

[neubig]

Fixed by #1871