Undefined window.dataLayer.push

[jacopocappelli1989]

Hi,
I've added module and works correctly but if I want to add some dataLayer for Enhanced Ecommerce I can't understand how do it.

In the App.js I've <GoogleTagManager gtmId={"GTM-myid"} /> and on product page, checkout ecc I try to add dataLayer but I can't understand how.

Can you help me?

Thanks very much