disable adsense on 404 pages in wordpress

disable_adsense.php

<?php

add_filter('widget_text', function( $content ) {
  $adsense = 'src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"';
    if ( is_404() ) {
        $content = str_replace( $adsense, '', $content );
    }
    return $content;
}, 1 );