TypeError when editing a fetched message from a partial webhook

[thegamecracks]

Summary

When editing a message that was fetched by a partial webhook, it fails with a TypeError.

Reproduction Steps

1. Create a partial webhook
2. Send a message and store the resulting WebhookMessage object
3. Re-fetch the message using fetch_message()
4. Attempt to edit the message

Minimal Reproducible Code

import asyncio
import aiohttp
import discord

async def main():
    async with aiohttp.ClientSession() as session:
        webhook = discord.Webhook.partial(1234, "token", session=session)
        message = await webhook.send("Hello world!", wait=True)
        message = await webhook.fetch_message(message.id)
        await message.edit(content="A whole new world!")

asyncio.run(main())

Expected Results

The message should have been edited.

Actual Results

The message is not edited, and the following error is raised:

Traceback (most recent call last):
  File "main.py", line 16, in <module>
    asyncio.run(main())
  File "..\Python311\Lib\asyncio\runners.py", line 190, in run
    return runner.run(main)
           ^^^^^^^^^^^^^^^^
  File "..\Python311\Lib\asyncio\runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "..\Python311\Lib\asyncio\base_events.py", line 653, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "main.py", line 14, in main
    await message.edit(content="A whole new world!")
  File "..\.venv\Lib\site-packages\discord\webhook\async_.py", line 892, in edit
    thread = Object(self._thread_id)
             ^^^^^^^^^^^^^^^^^^^^^^^
  File "..\.venv\Lib\site-packages\discord\object.py", line 77, in __init__
    id = int(id)
         ^^^^^^^
TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType'

Intents

N/A

System Information

..\.venv\Lib\site-packages\discord\__main__.py:33: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
  import pkg_resources
- Python v3.11.7-final
- py-cord v2.4.1-final
- aiohttp v3.8.6
- system info: Windows 10 10.0.22631

(note: actual operating system is Windows 11)

Checklist

• I have searched the open issues for duplicates.
• I have shown the entire traceback, if possible.
• I have removed my token from display, if visible.

Additional Context

Looking through the source code, it appears that this bug was introduced by d56dc86, where WebhookMessage._thread_id can be assigned None in fetch_message() while WebhookMessage.edit() assumes that the attribute can never be None.

pycord/discord/webhook/async_.py

Lines 1825 to 1827 in 9d4d0f7

	msg = self._create_message(data)
	if isinstance(msg.channel, PartialMessageable):
	msg._thread_id = thread_id

pycord/discord/webhook/async_.py

Lines 891 to 892 in 9d4d0f7

	if hasattr(self, "_thread_id"):
	thread = Object(self._thread_id)