Demystifying Async Programming in Javascript - co() error challenge

co-error-challenge.js

function deferred(val) {
  return new Promise((resolve, reject) => resolve(val));
}

function deferReject(e) {
  return new Promise((resolve, reject) => reject(e));
}

co(function* asyncAdds() {
  console.log(yield deferred('We are starting!'));
  try {
    console.log(yield deferReject(new Error('To fail, or to not fail.')));
  } catch (e) {
    console.log('We recovered!');
  }
  console.log(yield deferred('We finished!'));
});

function co(generator) {
  return new Promise((resolve, reject) => {
    // Your code goes here
  });
}