Use JQuery plugin with Webpack

I am trying to use the plugin Galleria with Webpack. Without Webpack galleria can be used as:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js"></script>
<script src="galleria/galleria-1.4.min.js"></script>

<script>
  (function() {
    Galleria.loadTheme('https://cdnjs.cloudflare.com/ajax/libs/galleria/1.5.7/themes/classic/galleria.classic.min.js');
    Galleria.run('.galleria');
  }());
</script>

The theme can also be loaded manually instead of using the method loadTheme:

<link rel=”stylesheet” type=”text/css” href=”https://cdnjs.cloudflare.com/ajax/libs/galleria/1.5.7/themes/fullscreen/galleria.classic.min.css” />

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js"></script>   
<script src=”https://cdnjs.cloudflare.com/ajax/libs/galleria/1.5.7/galleria.min.js”></script>
<script src=”https://cdnjs.cloudflare.com/ajax/libs/galleria/1.5.7/themes/classic/galleria.classic.min.js”></script>

<script>
  (function() {
    Galleria.run('.galleria');
  }());
</script>

With WebPack I added the following code to Index.js:

import galleria from 'galleria';

import '../../node_modules/galleria/dist/themes/classic/galleria.classic.css';
import '../../node_modules/galleria/dist/themes/classic/galleria.classic.js';

window.Galleria = galleria; 

(function() {
  Galleria.run('.galleria');
}());

When I run it I get the errors:

No theme CSS loaded.

Init failed: Galleria could not find the element "undefined".

Any idea how to use Galleria with Webpack?

from Use JQuery plugin with Webpack