Failure to download image for URL preview should not fail the whole preview

[turt2live]

Currently Synapse uses OpenGraph to try and find an image. If that fails, it'll pick an image from the DOM. If the image from either fails to download (403, 404, too large, etc) then Synapse should just return a preview without an image. Currently, it instead throws a 502 error instead.

[akontsevich]

This is preview from Skype, for example. However it is not the only problem: as I mentioned nothing from youtube works, many other sites like this: https://hdrezka-me.me/22654-teni-ischezayut-v-polden-95051943.html, livejournal, etc - nothing works actually.

[akontsevich]

Inserting new youtube link shows preview, however all previous links or on next days links are not previewed. So could be both synapse and client bugs.

[akontsevich]

Happen again today for some links, yesterday preview was normal for that link, for example:
https://rezka.ag/series/drama/13646-blokada.html

[Kevin-Mok]

I have a site hosting Twitch emotes that I used to reference to preview the emote. It was just working the last couple of days but suddenly stopped working. Previews from other images not on that site still work fine, so I'm not sure what happened.

It used to just work like this but now doesn't show anything, even though the link is still valid:

Edit: They started working again after a few hours.

[akontsevich]

Issue appeared again. Please fix!

[akontsevich]

URL preview is terrible: often show on strange languages like on screenshot below:
- text above should be on Russian. Definitely logic should be moved to client side!