ESP8266 "ERROR: Not connected to the internet" on save()

Hi, I'm trying to create server on ESP8266 and when I run code locally with USB cable connected it works fine, but when I save code to flash I get "Not connected to the internet" error.
I'm not sure what I do wrong or why is the internet connection required, because I'm not communicating with it. Can someone please help me?
I use STM32F4Discovery with 1.80.1 Espruino and MOD-WIFI-ESP8266 with 0.25 firmware version.
Code is below

Serial3.setup(115200, { rx: D9, tx : D8 });
var soc;
var wifi = require("ESP8266WiFi_0v25").connect(Serial3, function(err) {
  if (err) {digitalWrite(LED4,1);throw err;}
  //wifi.at.debug();
    console.log("Connecting to WiFi");
      wifi.connect("Espruino",'freeWifi', function(err) {
        if (err) throw err;
        console.log("Connected");
        require("net").createServer(function(c){
          console.log("incomming connection");
          c.on('data', onDataCallback);
          c.on('close', function(){
            console.log("bye");
          });
          soc = c;
        }).listen(8080);
        wifi.getIP(function(err,ip){
          if(err === null){
            console.log(ip);
            serverIP = ip;
            digitalWrite(LED2, 1);
          }
        });
  });
});

function onDataCallback(data){
  digitalWrite(LED1, !digitalRead(LED1));
  console.log("Server received: " + data);
  if(data !== undefined){
    if(data.length >= 6 && data.substr(0, 3).toLowerCase() == "led"){
      switch(data.charAt(3)){
        case '1':digitalWrite(LED1, data.charAt(5));break;
        case '2':digitalWrite(LED2, data.charAt(5));break;
        case '3':digitalWrite(LED3, data.charAt(5));break;
        case '4':digitalWrite(LED4, data.charAt(5));break;
      }
    }
    soc.write("Response: " + data);
    if(data.substr(0,4) == "exit")
      soc.end();
  }
}
save();