diff --git a/cms/topics/models.py b/cms/topics/models.py
index 4c6ba0ed..1c771ae7 100644
--- a/cms/topics/models.py
+++ b/cms/topics/models.py
@@ -126,16 +126,16 @@ def get_context(self, request: "HttpRequest", *args: Any, **kwargs: Any) -> dict
     @cached_property
     def latest_article_in_featured_series(self) -> StatisticalArticlePage | None:
         """Returns the latest article in the featured series."""
-        article: StatisticalArticlePage | None = StatisticalArticlePage.objects.none()
         if self.featured_series:
-            article = (
+            article: StatisticalArticlePage = (
                 StatisticalArticlePage.objects.child_of(self.featured_series)
                 .live()
                 .public()
                 .order_by("-release_date")
                 .first()
             )
-        return article
+            return article
+        return None
 
     @cached_property
     def processed_articles(self) -> list[ArticleSeriesPage]:
@@ -143,7 +143,7 @@ def processed_articles(self) -> list[ArticleSeriesPage]:
         TODO: extend when Taxonomy is in.
         """
         # check if any statistical articles were highlighted. if so, fetch in the order they were added.
-        highlighted_page_pks = tuple(page_id for page_id in self.related_articles.values_list("page_id", flat=True))
+        highlighted_page_pks = list(self.related_articles.values_list("page_id", flat=True))
         highlighted_pages = list(
             order_by_pk_position(
                 StatisticalArticlePage.objects.live().public().defer_streamfields(),
diff --git a/cms/topics/tests/test_viewsets.py b/cms/topics/tests/test_viewsets.py
index af76fa44..a74a960b 100644
--- a/cms/topics/tests/test_viewsets.py
+++ b/cms/topics/tests/test_viewsets.py
@@ -68,6 +68,15 @@ def test_chooser_search(self):
         self.assertNotContains(response, self.another_series.title)
         self.assertNotContains(response, self.another_topic.title)
 
+    def test_featured_series_viewset_configuration(self):
+        self.assertFalse(featured_series_page_chooser_viewset.register_widget)
+        self.assertEqual(featured_series_page_chooser_viewset.model, ArticleSeriesPageFactory._meta.model)
+        self.assertEqual(featured_series_page_chooser_viewset.choose_one_text, _("Choose Article Series page"))
+        self.assertEqual(
+            featured_series_page_chooser_viewset.choose_another_text, _("Choose another Article Series page")
+        )
+        self.assertEqual(featured_series_page_chooser_viewset.edit_item_text, _("Edit Article Series page"))
+
 
 class HighlightedPageChooserViewSetTest(WagtailTestUtils, TestCase):
     @classmethod
@@ -185,19 +194,6 @@ def test_methodology_results_view_with_topic_filter(self):
             [self.second_methodology],
         )
 
-
-class ViewSetConfigurationTest(TestCase):
-    """Test the configuration of the viewsets."""
-
-    def test_featured_series_viewset_configuration(self):
-        self.assertFalse(featured_series_page_chooser_viewset.register_widget)
-        self.assertEqual(featured_series_page_chooser_viewset.model, ArticleSeriesPageFactory._meta.model)
-        self.assertEqual(featured_series_page_chooser_viewset.choose_one_text, _("Choose Article Series page"))
-        self.assertEqual(
-            featured_series_page_chooser_viewset.choose_another_text, _("Choose another Article Series page")
-        )
-        self.assertEqual(featured_series_page_chooser_viewset.edit_item_text, _("Edit Article Series page"))
-
     def test_highlighted_article_viewset_configuration(self):
         self.assertFalse(highlighted_article_page_chooser_viewset.register_widget)
         self.assertEqual(highlighted_article_page_chooser_viewset.model, StatisticalArticlePageFactory._meta.model)