Check node being available on filtered queryset to prevent index error.

kolibri/core/content/api.py

@@ -969,8 +969,12 @@ def get_grandchild_ids(self, child_ids, depth, page_size):
 
     def get_tree_queryset(self, request, pk):
         # Get the model for the parent node here - we do this so that we trigger a 404 immediately if the node
-        # does not exist (or exists but is not available).
-        parent_id = pk if pk and self.get_queryset().filter(id=pk).exists() else None
+        # does not exist (or exists but is not available, or is filtered).
+        parent_id = (
+            pk
+            if pk and self.filter_queryset(self.get_queryset()).filter(id=pk).exists()
+            else None
+        )
 
         if parent_id is None:
             raise Http404

kolibri/core/content/test/test_content_app.py

@@ -422,6 +422,14 @@ def test_contentnode_tree(self):
         )
         self._recurse_and_assert([response.data], [root])
 
+    def test_contentnode_tree_filtered_queryset_node(self):
+        root = content.ContentNode.objects.get(title="root")
+        response = self.client.get(
+            reverse("kolibri:core:contentnode_tree-detail", kwargs={"pk": root.id})
+            + "?parent={}".format(uuid.uuid4().hex)
+        )
+        self.assertEqual(response.status_code, 404)
+
     @unittest.skipIf(
         getattr(settings, "DATABASES")["default"]["ENGINE"]
         == "django.db.backends.postgresql",