Images bridged from Discord with a message get deleted on Matrix's side if the message is edited

[salixor]

Currently, there's an issue with the bridge when a Discord user sends an image with a message.

The message on Matrix's side, as expected, is split between two events : one for the text of the message, the other for the image itself. As shown below :

Discord	Matrix

However, if the Discord user edits their message, the edit is appended to the image event, rather than the message event. This results in the following :

Discord	Matrix

On a side note, the same also happens if the Discord user :

• sends an image (with no text), which generates a m.image event
• edits the "message" by adding some text to the image
• in that case, there's only one event, and the m.image event is replaced

[dzaima]

duplicate of #859 & #797

[lewri]

Although a duplicate, I would argue that this issue is more informative to development than #797 is though for its thorough breakdown.