ESP8266 - Uncaught Error: Field or method does not already exist, and can't create it on undefined

Thanks! Yes, that's the one...

You might have luck with:

Serial4.setup(115200, { rx: C11, tx : C10 }); 
var wifi = require("ESP8266").connect(Serial4);
setTimeout(function() {   
wifi.connect("WiFi_Name","WPA2_Key", function() {   
}), 10000);

But I'm not sure - and even with that, built in ESP8266 support isn't good right now. The code from the thread will be a lot better.