Related to T245811#9042640, and other cases where text is created that MW won't save...

While the errors are just suppressed and "Publish" is a user apparent no-op (due to T342628: No error handling (effectively error suppression) on Special:PagePreparation), when it's more apparent, or the user doesn't want to save without making further edits, it would be useful if there was a way to take the "prepared" text from Special:PagePreparation into the edit box with ?action=edit.

An edit button could appear alongside "Publish" after "Prepare" is pressed.

With better error handling, it would stay enabled, whereas "Publish" would be disabled, making it clear to the user of a route to go forward.

It allows users to make other changes, or fix errors before clicking save.