PHP Fatal error on Ad Server Settings admin page

With the latest version of the plugin, going to the Ad Server Settings ([/wp-admin/edit.php?post_type=ad-layer&page=ad_layers_ad_server_settings](url)) page in wp-admin throws the following exception, resulting in a fatal error:

`PHP Fatal error: Uncaught exception 'FM_Submenu_Not_Initialized_Exception' with message 'The Fieldmanger context for this submenu was not initialized'`

This renders the plugin no longer fully configurable via the wp-admin UI.