Webix and requirejs

If you will use webix and requirejs together, you will get an error like this.

TypeError: window.html2canvas is not a function
    toPNG topng.js:31
    u promiz.js:310
    a promiz.js:286
    u promiz.js:301
    <anonymous> promiz.js:15
    EventListener.handleEvent* promiz.js:8
    <anonymous> webix.js:8
    <anonymous> webix.js:8

https://snippet.webix.com/85no2xtr

there is something wrong with html2canvas library itself in connection with requirejs.
but if the library script is loaded explicitly before requirejs, then it works.
https://snippet.webix.com/34hnx662