How to create user by Nativescript firebase plugin?

Question

I'm using EddyVerbruggen's NativeScript firebase plugin - https://github.com/EddyVerbruggen/nativescript-plugin-firebase

Firebase has been configured properly. I ran the following code & it's working fine.

firebase.init(<any>{
    persist: true, // Allow disk persistence. Default false.
    url: config.apiUrl
}).then(
    function (instance) {
        console.log("firebase.init done");
    },
    function (error) {
        console.log("firebase.init error: " + error);
    }
);

But, when I'm trying to create user through email id & password by using following code

firebase.createUser({
    email: 'eddyverbruggen@gmail.com',
    password: 'firebase'
}).then(
    function (result) {
        // dialogs.alert({
        //  title: "User created",
        //  message: "userid: " + result.key,
        //  okButtonText: "Nice!"
        // })
        alert('User Created with user id - '+result.key);
    },
    function (errorMessage) {
        // dialogs.alert({
        //  title: "No user created",
        //  message: errorMessage,
        //  okButtonText: "OK, got it"
        // })
        alert('No user created. Got error message insted - '+errorMessage);             
    }
)

I'm getting message from my console like this -

JS: --- auth state changed: com.google.android.gms.internal.zzadg@399fbe6

The main parent file is -

import {Injectable} from "@angular/core";
import {User} from "./user";
import {ConfigService} from "../config";
import firebase = require("nativescript-plugin-firebase");

@Injectable()
export class UserService {

    register(user: User,config:ConfigService) {
        alert("API url going to use is : "+config.apiUrl);

        firebase.init(<any>{
            persist: true, // Allow disk persistence. Default false.
            url: config.apiUrl
        }).then(
            function (instance) {
                console.log("firebase.init done");
            },
            function (error) {
                console.log("firebase.init error: " + error);
            }
        );

        firebase.createUser({
            email: 'eddyverbruggen@gmail.com',
            password: 'firebase'
        }).then(
            function (result) {
                // dialogs.alert({
                //  title: "User created",
                //  message: "userid: " + result.key,
                //  okButtonText: "Nice!"
                // })
                alert('User Created with user id - '+result.key);
            },
            function (errorMessage) {
                // dialogs.alert({
                //  title: "No user created",
                //  message: errorMessage,
                //  okButtonText: "OK, got it"
                // })
                alert('No user created. Got error message insted - '+errorMessage);
            }
        )

    }
}

when in checking in my firebase app account user account also not reflecting.

I know, there is a small mistake, because of which it's not working. But, can't able to figure out what causing the problem.

-------Error Fixed-------

Whole time I was testign in an Emulator which has no Google Play Service installed. It required Google Play Service to work. Finally, when I tested this in my mobile device it's worked fine.