problems with webpack packaging fullPage.js

fullPage.js is a single screen scrolling plug-in

address on github

https://github.com/alvarotrig.

if you just flip up and down pages, introduce

import "fullpage.js"

there is no problem with this.

but if the content on a page exceeds the size of the current page, if you want the page to have a scroll bar, you must configure a property

        $("-sharpfullpage").fullpage({
            scrollOverflow: true
        })

another file scrolloverflow.min.js will be introduced

in the case of not using webpack packaging, direct < script > introduction of this file is a normal scroll bar

but packaged with webpack, in main.js

import "fullpage.js"
import "fullpage.js/vendors/scrolloverflow"

will report an error

scrolloverflow.js?1f13:2392 Uncaught ReferenceError: IScroll is not defined

what I want to ask is

1. how can I use webpack to package fullpage.js and scrolloverflow.min.js together
2. Why did you report the error IScroll is not defined

ask the Great God for advice