Fix comments snippet admin 500

Use an explicit Wagtail Column for pending_in_article in CommentViewSet list_display and add a regression test for /cms/snippets/comments/comment/.

Fixes #37

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

apps/comments/tests/test_admin.py

@@ -1,4 +1,5 @@
 import pytest
+from django.test import override_settings
 
 from apps.blog.models import ArticleIndexPage, ArticlePage
 from apps.blog.tests.factories import AuthorFactory
@@ -79,3 +80,18 @@ def test_bulk_approve_action_marks_selected_pending_comments_as_approved(home_pa
     assert child_updates == 0
     assert pending.is_approved is True
     assert approved.is_approved is True
+
+
+@pytest.mark.django_db
+@override_settings(ALLOWED_HOSTS=["testserver", "localhost", "127.0.0.1"])
+def test_comments_snippet_index_page_loads(client, django_user_model, home_page):
+    admin = django_user_model.objects.create_superuser(
+        username="admin",
+        email="admin@example.com",
+        password="admin-pass",
+    )
+    client.force_login(admin)
+
+    response = client.get("/cms/snippets/comments/comment/")
+
+    assert response.status_code == 200