isWindows is not a function, when webpacked

[autotel]

This is used as dependency in "audio-loader" library. This is my context.
After transpiling my code with webpack, including the "audio-loader" library, the library fails because "isWindows is not a function". The library, however ran well when not transpiled.
I did a dirty patch, replacing the first lines of "./is-absolute/index.js" as:

'use strict';

var isRelative = require('is-relative');
var isWindows = require('is-windows');
if(typeof isWindows!="function") isWindows=()=>true;

I can't imagine why in the world the "isWindows" is exporting a boolean, and less why it is doing so only after webPacking it.

[MilesMorel]

Just ran into the same thing...