Embedded vals sometimes fail to load

[Xkonti]

Embedded vals sometimes fail to load, which leads to confusion. Often a refresh works, but sometimes it takes more than one.

https://discord.com/channels/1020432421243592714/1020432421243592717/threads/1206842458554634240

There are 2 approaches possible:

• Replace existing embeds with code blocks - this is the most stable approach, but it doesn't enable browser preview
• Improve embeds' stability - something probably outside of the docs

[maxmcd]

I ran into a similar issue where a val.town embed was returning a 401 because my jwt had expired and the error page was returning x-frame-options:deny. Visiting val.town and then returning to the embed fixed things.

Might want to gracefully handle auth failures in vals and not deny the iframe on embed error responses.