docs: def get_hidden_fields_errors(self, form):
          '''Returns a dict to add in response when something is wrong with hidden fields'''
          if not self.include_hidden_fields or form.is_valid():
              return {}
  
          response = {self.hidden_field_error_key:{}}
  
          for field in form.hidden_fields():
              if field.errors:
                  response[self.hidden_field_error_key][field.html_name] = self._get_field_error_dict(field)
          return response