do not throw error directly for generator. always wrap in a callback ?

wrap_errors_for_generators.es.js

// works: https://gist.github.com/deepak/ffe01c81900d12f95658
// does not work: https://gist.github.com/deepak/9a7337d7a641f8af9c8b

// difference is that, if error is thrown directly from fucntion called in generator
// then it gives a "Generator is already running" error
// but if it is wrapped in a setTimeout callback then it works

// WORKS

let price = 10;
 
let stockPrice = function () {
  setTimeout(function() {
    iterator.next(price++);
  }, 300);
}

let errorInStockPrice = function() {
  setTimeout(function() {
    iterator.throw("oops!");
  }, 300);
}

let stockTicker = function*() {
  try {
    price = yield stockPrice();
    console.log("price is " + price); //=> price is 10
    
    price = yield errorInStockPrice();
    console.log("price is " + price); //=> price is 10
  
    price = yield stockPrice();
    console.log("price is " + price); //=> price is 10
  } catch (ex) {
    console.log("error in stock-price: " + ex); //=> error in stock-price: Error: oops!
  }
};
 
var iterator = stockTicker();
console.log(iterator.next()); //=> {"done":false}

// DOES NOT WORK

let price = 10;
 
let stockPrice = function () {
  setTimeout(function() {
    iterator.next(price++);
  }, 300);
}

let badErrorInStockPrice = function() {
  iterator.throw("oops!");
}
 
let stockTicker = function*() {
  try {
    price = yield stockPrice();
    console.log("price is " + price); //=> price is 10
    
    price = yield badErrorInStockPrice();
    console.log("price is " + price); //=> price is 10
  
    price = yield stockPrice();
    console.log("price is " + price); //=> price is 10
  } catch (ex) {
    console.log("error in stock-price: " + ex); //=> 
    //=> error in stock-price: Error: Generator is already running
    // expected, error in stock-price: Error: oops!
  }
};
 
var iterator = stockTicker();
console.log(iterator.next()); //=> {"done":false}

continuation of https://gist.github.com/deepak/ffe01c81900d12f95658
and https://gist.github.com/deepak/9a7337d7a641f8af9c8b