How to catch status 503 in tampermonkey

I have a userscript that refreshes the page every second, but sometimes the website it's trying to refresh runs into the status 503 error, and that stops the script from running anymore. That means that script will no longer try refresh the page every second. How do I keep the script running after the page runs into the status 503 error? The error looks like this in the console:

Failed to load resource: the server responded with a status of 503 (Service Unavailable)

// ==UserScript==
// @name        script
// @namespace   name
// @description example
// @match       *^https://example.com/$*
// @version     1
// @require     https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js
// @grant       GM_xmlhttpRequest
// @run-at document-end
// ==/UserScript==

//*****************************************START OF SET_TIMEOUT
var timeOne = 1000;
var theTime = timeOne;

var timeout = setTimeout("location.reload(true);", theTime);
function resetTimeout() {
clearTimeout(timeout);
timeout = setTimeout("location.reload(true);", theTime);
} //end of function resetTimeout()
//*****************************************END OF SET_TIMEOUT

from How to catch status 503 in tampermonkey