Nested Widget validation not highlighting parent widget in red

The widget validation does not highlight the field under validation in red, in case of deeply nested widgets.
This makes it really hard to find the offending field if there are many collapsed widgets on the page.

For example, my setup is using the `netlify-cms-app`, where I have a `list` widget of variable object type.
This list has several types of "component" widgets, which are all built using `object` or `list` widgets and contain widgets of all other types, like `string`, `number` etc.

I just now realized, that validation errors aren't displayed **at all**, you can only see if a validation failed if all widgets are extended and not collapsed.

On the other hand, error of type `required`, display just fine with helpful highlighting of borders all the way up from the offending widget field to the parent widget.