Reproduce:

- Go to admin, custom fields, user
- Create two or more required user custom fields
- Logout, click register
- Click save without entering anything

Expected: For each missing but required custom field a single error is shown
Result: For each missing but required custom field, all errors for these custom fields are shown an additional times. So for 3 required custom fields and all missing, there are 9 error messages shown. Begin of the deletion
End of the deletion