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/wagtail_hooks.py

@@ -4,7 +4,7 @@ from django.db.models import Count, Q
 from django.utils.translation import gettext_lazy as _
 from django.utils.translation import ngettext
 from wagtail import hooks
-from wagtail.admin.ui.tables import BooleanColumn
+from wagtail.admin.ui.tables import BooleanColumn, Column
 from wagtail.snippets.bulk_actions.snippet_bulk_action import SnippetBulkAction
 from wagtail.snippets.models import register_snippet
 from wagtail.snippets.permissions import get_permission_name
@@ -45,7 +45,13 @@ class CommentViewSet(SnippetViewSet):
     model = Comment
     queryset = Comment.objects.all()
     icon = "comment"
-    list_display = ["author_name", "article", BooleanColumn("is_approved"), "pending_in_article", "created_at"]
+    list_display = [
+        "author_name",
+        "article",
+        BooleanColumn("is_approved"),
+        Column("pending_in_article", label="Pending (article)"),
+        "created_at",
+    ]
     list_filter = ["is_approved"]
     search_fields = ["author_name", "body"]
     add_to_admin_menu = True
@@ -62,11 +68,5 @@ class CommentViewSet(SnippetViewSet):
             )
         )
 
-    def pending_in_article(self, obj):
-        return obj.pending_in_article
-
-    pending_in_article.short_description = "Pending (article)"  # type: ignore[attr-defined]
-
-
 register_snippet(CommentViewSet)
 hooks.register("register_bulk_action", ApproveCommentBulkAction)