If I try to use fetch like so:
let response = await fetch('https://domain.tld');
Uglify throws this error:
Unexpected token: name «fetch», expected: punc «;».
This old issue (#499) appears to be similar, but the solution is to use a grunt package that is currently marked as depreciated so ¯\_(ツ)_/¯
I'm using grunt-contrib-uglify version 5.2.1