Why does this not work

update-portal-links.user.js

// ==UserScript==
// @name Update mailhog links sometimes
// @description  Update broken Links in mailhog
// @author Andrew Wylde <https://codelemur.com/>
// @match *localhost:8025*
// @namespace    http://tampermonkey.net/
// @version      1.0.0
// @updateURL    https://gist.github.com/codelemur/0973624c0e1ec014561c68a6b28a2117/raw/update-portal-links.user.js
// @downloadURL  https://gist.github.com/codelemur/0973624c0e1ec014561c68a6b28a2117/raw/update-portal-links.user.js
// @require http://code.jquery.com/jquery-3.4.1.min.js
// ==/UserScript==

(function() {
    'use strict';
    let hasEdited = false;
    let intervalRef = setInterval(() => {
        if (hasEdited) {
            clearInterval(intervalRef);
        } else {
            const correctURL = decodeURIComponent($('#preview-html').contents().find('a:last').prop('textContent').replaceAll('.=','=').replaceAll('=\n','.').replaceAll('-.','-').replaceAll('=3D','='));
            $('#preview-html').contents().find('a').attr('href',correctURL);
            hasEdited = true;
        }
    }, 500)
})();