Admin path destination breaks on subdirectory installations

hi,

just figured a minor issue while playing around with the module on D8:

in _ds_field_ui_table_layouts_preview, $admin_path leads to a not found redirect. as the SITE_SUB_URL is included:

$admin_path = \Drupal::service('url_generator')->generateFromRoute($route_name, $route_parameters, $options);

admin/structure/ds/change-layout/node/article/default/ds_2col_stacked?destination=/SITE_SUB_URL/admin/structure/types/manage/article/display

this might be a D8 issue by itself...?