For others who might get the same problem I did.
I have installed GSAP through npm. I then added the customEase lib
"../.../vendor/customEase.min.js"
My customEase was then not able to find the TweenLite lib which it needs to work. In the customEase lib TweenLite is referred:
require("./TweenLite.js")
So I just changed it to
require("gsap")
I also import the customeEase.min.js in my index.ts file.
In my greensock.d.ts i declared:
interface CustomEase {
create(id:string, data:string):CustomEase;
get(id:string):CustomEase;
getRatio(progress:number):CustomEase;
}
declare var CustomEase:CustomEase;