🐛 Add explicit checks for chunksize value

Author: Paillat-dev

discord/message.py

@@ -314,7 +314,7 @@ async def save(
             deleted attachments if too much time has passed, and it does not work
             on some types of attachments.
         chunksize: Optional[:class:`int`]
-            The maximum size of each chunk to process.
+            The maximum size of each chunk to process. Must be a positive non-null integer.
 
         Returns
         -------
@@ -331,6 +331,8 @@ async def save(
             Argument `chunksize` is less than 1.
         """
         if chunksize is not None:
+            if chunksize < 1:
+                raise InvalidArgument("chunksize must be a positive non-null integer.")
             data = self.read_chunked(use_cached=use_cached, chunksize=chunksize)
         else:
             data = await self.read(use_cached=use_cached)