fix: mypy issues (#1667)

Author: jorwoods

test/test_custom_view.py

@@ -141,9 +141,11 @@ def test_update(server: TSC.Server) -> None:
         the_custom_view = TSC.CustomViewItem("1d0304cd-3796-429f-b815-7258370b9b74", name="Best test ever")
         the_custom_view._id = "1f951daf-4061-451a-9df1-69a8062664f2"
         the_custom_view.owner = TSC.UserItem()
+        assert the_custom_view.owner is not None  # for mypy
         the_custom_view.owner.id = "dd2239f6-ddf1-4107-981a-4cf94e415794"
         the_custom_view = server.custom_views.update(the_custom_view)
 
+    assert isinstance(the_custom_view, TSC.CustomViewItem)
     assert "1f951daf-4061-451a-9df1-69a8062664f2" == the_custom_view.id
     if the_custom_view.owner:
         assert "dd2239f6-ddf1-4107-981a-4cf94e415794" == the_custom_view.owner.id