generic-error-page.html
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
const something_abc1 = "abc";
const something_abc2 = "abc2";
</script>
<style>
.css{background:blue;}
.test2{
background:red;
}
</style>
<script type="text/javascript" src="/some-url.js"></script>
<script type="text/javascript" src="/some-url2.js"></script>
<link rel="stylesheet" href="/some-url.css" />
<link rel="stylesheet" href="/some-url2.css" />
</head>
<body>
<!-- TEST THEME -->
<h1>Error</h1>
<p>An unkown error has occured</p>
</body>
</html>