Webpack and MooTools

Question

I have a JS App, that uses MooTools 1.4.5, and it works fine. MooTools is included by using tags in index.html:

<script type="text/javascript" src="./frameworks/mootools-core-1.4.5-full-compat.js"></script>

Now I am doing a rework of the project, will use webpack to build the app, and I run into an issue when loading MooTools. This line:

require('../frameworks/mootools-core-1.4.5-full-compat.js');

causes this error to be reported:

Uncaught ReferenceError: Slick is not defined

It seems as if the the require call is not able to properly load MooTools. Did somebody else encounter this issue? I am not able to figure out why this happens.

Thanks