repliedMessageOrNull
Attempt to retrieve the message that the current message is in reply to, if any.
In some situations, such as when dealing with a cross-posted (forwarded) message, Discord may return an HTTP 403. This function returns null in those situations.
This function also returns null when the messages come from different channels, to avoid cross-posted messages.
Return
Corresponding Message object if found, accessible, and correct; null otherwise.