First of all thank you for providing this library.
We have recently starting experiencing an Uncaught DOMException: Failed to execute 'atob' on 'Window' on use of this library.
I think the meaning of use strict; (at least on chrome) has recently got a lot more strict and the use of the non-imported atob and btoa in this library is now causing an Uncaught DOMException.
As far as I can see, replacing atob and btoa with window.atob and window.btoa makes things work again but I'm uncertain as to whether this is the correct approach.