var linkList = window.document.querySelectorAll(".Groups__item");
let arr = [];

window.console.log("Links count: ", linkList.length);

for (i=0; i <= linkList.length; i++){
var linkList = window.document.querySelectorAll(".Groups__item")[i].href
arr.push(linkList)
window.console.log(i);
}

var countLink = linkList.length;

window.console.log("Links count: ", countLink);

for (i=1; i <= countLink; i++){
var linkList = window.document.querySelectorAll(".Groups__item")[i].href
arr.push(linkList)
window.console.log(i);
}

for (i=1; i <= countLink; i++){
arr.push(window.document.querySelectorAll(".Groups__item")[i].href);
window.console.log(i);
}

TypeError: window.document.querySelectorAll(...)[i] is undefined, line 8 (Error code: -991)