comment fixup

adhocracy4/comments_async/api.py

@@ -1,14 +1,14 @@
 from django.apps import apps
 from django.conf import settings
 from django.contrib.contenttypes.models import ContentType
-from django.core.exceptions import PermissionDenied
 from django.urls import reverse
 from django.urls.exceptions import NoReverseMatch
 from django.utils.translation import gettext_lazy as _
 from django_filters import rest_framework as filters
 from rest_framework import mixins
 from rest_framework import status
 from rest_framework import viewsets
+from rest_framework.exceptions import ValidationError
 from rest_framework.pagination import PageNumberPagination
 from rest_framework.response import Response
 
@@ -134,9 +134,10 @@ def _save_terms_agreement(self):
                     }
                 )
             else:
-                raise PermissionDenied(
+                raise ValidationError({
+                    'comment':
                     _("Please agree to the organisation's terms of use.")
-                )
+                })
 
     def perform_create(self, serializer):
         self._save_terms_agreement()