If you are doing this:

const req = {req: {item_name: "variables"}};
let bad_req = req;
delete bad_req.req.item_name; // this also changes req;
let another_test_req = req; // req is missing item_name here

You need to use Object.freeze() to prevent keys_req from being changed as well:

const req = Object.freeze({req: {item_name: "variables"}});