$anyError should check $error on children instead of $anyDirty

[Akryum]

Currently $anyError uses this expression according to the docs:

this.$anyDirty && !this.$pending && this.$invalid

This is wrong because a form can be $invalid and $anyDirty but not having any single $error in the validation tree.

For example, you only have required fields.

1. The form is { $invalid: true, $anyDirty: false, $anyError: false } and no errors are displayed (yet)
2. The user enter something in the first field, making it valid
3. We touch the field so it becomes $dirty
4. No error are show yet, because the other fields aren't $dirty (the user hasn't come to those yet)
5. The form is now { $invalid: true, $anyDirty: true, $anyError: true }

It should be { $invalid: true, $anyDirty: true, $anyError: false } because we don't display any error.

This is very anoying if we want to disable the submit button as long as at least one error is shown.

[pareeohnos]

Any ETA on getting this merged? Running into this in our system and would like to get it finished up