holy shit seems where i'm right now (taiwan) was some strange filtering going on or webfiltering or whatever. now everything works fine, i think was a internet problem here ... sorry for bothering ...
i would love to have a look at the project but your website is not working.
from the 3 assets you provide is only the app.css available, vendor.js + bundle.js not found.
you should have a look in your build task :)
<!doctype html>
<html>
<head>
<title>Unstuck Webpack</title>
<link rel="stylesheet" href="app.css" />
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
</head>
<body>
<div id="application" class="application"></div>
<script src="vendor.js"></script>
<script src="bundle.js"></script>
</body>
</html>