This type is mainly referenced through .ui files, which doesn't give an opportunity to ensure the type is registered before building the UI from templates.
Since GTK templates are implemented vala attributes, do this in main() to ensure this happens before the construction of the relevant types/classes.
This fixes the UI to edit settings (e.g. after clicking in the list), previously this would fail with a number of warnings, starting with:
(dconf-editor:51218): Gtk-CRITICAL **: 19:31:57.751: Error building template class 'RegistryInfo' for an instance of type 'RegistryInfo': .:18:665 Invalid object type 'RegistryWarning'