Prevent auto-save if the field doesn't pass validation

The auto-save examples really help but there is one thing that I couldn't figure out.
How to prevent submission if the field doesn't pass the validation.

Also in the example https://codesandbox.io/s/5w4yrpyo7k if you change a field into being empty after it has been filled, the diff object is empty instead of an object with the field name key with the value empty string