Auto-populate post title from featured image title

function get_featured_image_title( $post_id )  {
    $attachment_id = get_post_thumbnail_id( $post_id );
    if ( ! $attachment_id ) {
        return false;
    }

    $attachment_data = wp_get_attachment_metadata( $attachment_id );
    if ( ! isset( $attachment_data['image_meta']['title'] ) ) {
        return false;
    }

    return $attachment_data['image_meta']['title'];
}

function disable_empty_content_check( $maybe_empty, $postarr ) {
    if ( ! $maybe_empty ) {
        return $maybe_empty;
    }

    if ( 'showcase' !== $postarr['post_type'] ) {
        return $maybe_empty;
    }

    if ( wp_is_post_revision( $postarr['ID'] ) ) {
        return $maybe_empty;
    }

    if ( get_featured_image_title( $postarr['ID'] ) ) {
        $maybe_empty = false;
    }

    return $maybe_empty;
}
add_filter( 'wp_insert_post_empty_content', 'disable_empty_content_check', 10, 2 );

function auto_populate_post_title( $data, $postarr ) {
    if ( 'showcase' !== $postarr['post_type'] ) {
        return $data;
    }

    if ( wp_is_post_revision( $postarr['ID'] ) ) {
        return $data;
    }

    $featured_image_title = get_featured_image_title( $postarr['ID'] );
    if ( ! $data['post_title'] && $featured_image_title ) {
        $data['post_title'] = $featured_image_title;
    }

    return $data;
}
add_filter( 'wp_insert_post_data', 'auto_populate_post_title', 10, 2 );