ignoring errors in delegated generators

[jonathanong]

i ran into a really weird issue that i finally simplified to a small test case:

function* top() {
  try {
    yield* bottom()
  } catch (err) {
    console.log('caught an error: ' + err.message)
  }
}

function* bottom() {
  try {
    yield undefined
  } catch (err) {
    return // ignore the error
  }
}

var gen = top()
console.log(gen.next())
console.log(gen.throw(new Error('lol')))

i want to ignore specific errors in bottom(). in node 0.11, the result is correct:

{ value: undefined, done: false }
{ value: undefined, done: true }

but in regenerator (specifically gnode) i get:

{ value: undefined, done: false }
caught an error: lol
{ value: undefined, done: true }

seems like regenerator isn't ignoring the error or something. here's the compiled code:

wrapGenerator.mark(bottom);
wrapGenerator.mark(top);

function top() {
  return wrapGenerator(function top$($ctx0) {
    while (1) switch ($ctx0.next) {
    case 0:
      $ctx0.pushTry(5, null, null);
      return $ctx0.delegateYield(bottom(), "t0", 2);
    case 2:
      $ctx0.popCatch(5);
      $ctx0.next = 9;
      break;
    case 5:
      $ctx0.popCatch(5);
      $ctx0.t1 = $ctx0.thrown;
      delete $ctx0.thrown;
      console.log('caught an error: ' + $ctx0.t1.message);
    case 9:
    case "end":
      return $ctx0.stop();
    }
  }, this);
}

function bottom() {
  return wrapGenerator(function bottom$($ctx1) {
    while (1) switch ($ctx1.next) {
    case 0:
      $ctx1.pushTry(6, null, null);
      $ctx1.next = 3;
      return undefined;
    case 3:
      $ctx1.popCatch(6);
      $ctx1.next = 12;
      break;
    case 6:
      $ctx1.popCatch(6);
      $ctx1.t2 = $ctx1.thrown;
      delete $ctx1.thrown;
      delete $ctx1.thrown;
      $ctx1.next = 12;
      break;
    case 12:
    case "end":
      return $ctx1.stop();
    }
  }, this);
}

var gen = top();
console.log(gen.next());
console.log(gen.throw(new Error('lol')));