Use generators with promises for better error handling. :)

run.js

/*  
  Let `a` be a Promise. To make the generator wait for a to resolve, 
  simply `yield a`. By default, all rejected Promises throw an error
  in our generator. Yield an iteratable to get an array of resolved 
  values.
*/

function isIterable(object) {
  return Symbol.iterator in Object(object);
}

function run(generator, ...args) {
  let iterator = generator(...args);
  next(iterator.next(), iterator);
}

function next({value, done}, iterator) {
  if (done) return;
  const method = isIterable(value) ? 'all' : 'resolve';
  
  Promise[method](value)
    .then((result) => {
      next(iterator.next(result), iterator);
    })
    .catch((error) => {
      iterator.throw(error);
    });
}