Off-screen validation errors should be highlighted/indicated in the viewport

[turnstylerj]

Especially on larger entries, it's sometimes difficult to see why an entry isn't saving if there's a field validation error that's since been scrolled off-screen.

It would be nice to have a little fixed indicator like Slack does with off-screen unreads:

with a red pill and the text "1 validation error", which would go away once the error is scrolled into view.