Telegram private stickers are not properly handled and fail to fetch the sticker image

[drjaska]

Telegram has a feature where someone can have a private sticker collection from which they can send stickers from and those stickers can't be copied (though they can be forwarded) in the Telegram app. When these stickers are bridged to matrix the message seems to be bridged fine except that the image is still missing. Element Mobile just displays a void instead of the image and Element Desktop shows "Unable to show image due to error".

If other bridges such as mautrix-discord attempt to bridge these messages then they will complain about image 404'ing:

Your message may not have been bridged: failed to GET /_matrix/client/v1/media/download//: M_NOT_FOUND (HTTP 404): Not found '/_matrix/client/v1/media/download//'

I would suggest fixing the image ripping, if this is not possible then handle the messages specially as needed.

[zouppen]

I can confirm that it causes notable error message mess in some channels which are bridged with both mautrix-telegram and mautrix-discord.

[tulir]

Missing logs and event source