FacetWP - set default slider "start" values

gistfile1.php

<?php

function my_facetwp_render_output( $output, $params ) {
    $facet_name = 'YOUR_FACET_NAME'; // CHANGE ME

    foreach ( $params['facets'] as $facet ) {
        if ( $facet_name == $facet['facet_name'] && empty( $facet['selected_values'] ) ) {
            $output['settings'][ $facet_name ]['start'] = array( 10, 50 );
        }
    }
    return $output;
}
add_filter( 'facetwp_render_output', 'my_facetwp_render_output', 10, 2 );