this is dead simple html code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/simplebar/4.2.3/simplebar.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/simplebar/4.2.3/simplebar.min.css">
<script>
$(document).ready(function() {
new SimpleBar();
})
</script>
</head>
<body>
dd
</body>
</html>
and I wonder why I get this error message. thx