Fixing Slice Machine

One of our devs seems to have messed up something with Slice Machine and accidentally deleted a couple of slice types. This was devastating, since it looks like those slices got removed out of every document that had them, and they are gone from the history of those docs as well.

In any case, after trying to restore the slice types, I'm seeing this "Error" in the prismic UI but there's no indicator of what's wrong other than the red word "Error". How do I diagnose and debug this error?

This type of error is usually related to the Live Preview URL configuration. If the URL is set to localhost, only developers will have access. In this case, updating it to the live site URL should allow access to editors