docs: def form_invalid(self, form, prefix=None):
          """ If form invalid return error list in JSON response """
          response = super(FormAjaxMixin, self).form_invalid(form)
          if self.request.is_ajax():
              data = {
                  "errors_list": self.add_prefix(form.errors, prefix),
              }
              return self.json_to_response(status=400, json_data=data,
                                           json_status=AjaxResponseStatus.ERROR)
          return response