give error handler a chance to attach

fixes https://github.com/tessel/runtime/issues/509

Previously this worked:

```js
wifi.on('error', function(err){
	console.log("error", err);
});

wifi.connect({
    security: "wpa2"
    , ssid: new Buffer("test")
    , password: "test"
    , timeout: 10
});
```

But this did not:

```js
wifi.connect({
    security: "wpa2"
    , ssid: new Buffer("test")
    , password: "test"
    , timeout: 10
});

wifi.on('error', function(err){
	console.log("error", err);
});
```