Remove sidebars and footer widgets on 404 page

gistfile1.txt

add_filter( 'generate_sidebar_layout', 'tu_remove_sidebars' );
function tu_remove_sidebars( $sidebar ) {
  if ( is_404() ) {
    return 'no-sidebar';
  }
  
  return $sidebar;
}

add_filter( 'generate_footer_widgets', 'tu_remove_footer_widgets' );
function tu_remove_footer_widgets( $widgets ) {
  if ( is_404() ) {
    return '0';
  }
  
  return $widgets;
}