Arguments Optional return undefined but why?

Tell us what’s happening:
At the last step:
console.log(args[0] + args[1]); // 5
return args[0] + args[1]; // undefined

I can’t find the bug…

Your code so far

"use strict";
function addTogether() {
    let args = [...arguments];
    if (!(args.every((val) => (typeof val) == "number"))) {
        return undefined;
    if (args.length < 2) {
        return function(secondNumber) {
            addTogether(secondNumber, args[0]);
    console.log(args[0] + args[1]);
    return args[0] + args[1];


Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36 OPR/60.0.3255.95.

Link to the challenge:

The returned function doesn’t have a return statement, so it is returning undefined