visionmedia/co — pull request #67 by logicalparadox (2014-01-01 09:15:17+00:00)
Title: bug: nil argument in first position replaced with error fn

If invoking with nil argument (`0`, `null`, `false`) as first argument to generator function it would be replaced with the `error` function.

```js
co(function*(bln) {
bln.should.be.a('boolean'); // => fails (equals [Function: error])
})(false, done);
```