generator receiving exceptions

generator_simple.harmony.js

var catchingGenerator = function *(){
    console.log('I will stop when you tell me about error');
    var error = null;
    while(error === null){
      try {
        var value = yield null;
        console.log("Got value from you: %s", value);
      }catch(e){
        error = e;
      }
    }
    console.log('Got error from you: %s. Goodbye!', error);
};

var throwingGenerator = catchingGenerator();
throwingGenerator.next("Wait for error");
throwingGenerator.next("I will throw in a moment!");

throwingGenerator.throw("This is the end");