fix: (Sync)WebhookMessage._thread_id could be None (#2343)

* fix: check if thread_id is None

* chore: add changelog entry

CHANGELOG.md

@@ -230,6 +230,8 @@ These changes are available on the `master` branch, but have not yet been releas
   ([#2333](https://github.com/Pycord-Development/pycord/issues/2333))
 - Fixed `BridgeContext` type hints raising an exception for unsupported option type.
   ([#2337](https://github.com/Pycord-Development/pycord/pull/2337))
+- Fixed `TypeError` due to `(Sync)WebhookMessage._thread_id` being set to `None`.
+  ([#2343](https://github.com/Pycord-Development/pycord/pull/2343))
 
 ## [2.4.1] - 2023-03-20
 

discord/webhook/async_.py

@@ -1855,7 +1855,7 @@ async def fetch_message(
             thread_id=thread_id,
         )
         msg = self._create_message(data)
-        if isinstance(msg.channel, PartialMessageable):
+        if thread_id and isinstance(msg.channel, PartialMessageable):
             msg._thread_id = thread_id
 
         return msg

discord/webhook/sync.py

@@ -1147,7 +1147,7 @@ def fetch_message(
             thread_id=thread_id,
         )
         msg = self._create_message(data)
-        if isinstance(msg.channel, PartialMessageable):
+        if thread_id and isinstance(msg.channel, PartialMessageable):
             msg._thread_id = thread_id
 
         return msg