How do I integrate Google plus login in my ionic app

I did this stuff below

import { Component } from '@angular/core';
import { NavController,Platform, LoadingController} from 'ionic-angular';
import { SharedService } from '../../providers/sharedservice/sharedservice';
import { Facebook, FacebookLoginResponse } from '@ionic-native/facebook';
import { QuestionPage } from '../question/question';
import { GooglePlus } from '@ionic-native/google-plus';

@Component({
  selector: 'page-login',
  templateUrl: 'login.html',
})
export class LoginPage {
  questionPage=QuestionPage;
  constructor(public loadingCtrl: LoadingController,public navCtrl: NavController,public platform: Platform,public sharedService:SharedService, public fb:Facebook, private  googlePlus: GooglePlus) {
  }

  ionViewDidLoad() {
    console.log('ionViewDidLoad LoginPage');

  }
  fb_login()
  {
      // Login with permissions
      this.fb.login(['public_profile', 'user_photos', 'email', 'user_birthday'])
      .then( (res: FacebookLoginResponse) => {

          // The connection was successful
          if(res.status == "connected") {

              // Get user ID and Token
              var fb_id = res.authResponse.userID;
              var fb_token = res.authResponse.accessToken;

              // Get user infos from the API
              this.fb.api("/me?fields=name,gender,birthday,email", []).then((user) => {

                  // Get the connected user details
                  var gender    = user.gender;
                  var birthday  = user.birthday;
                  var name      = user.name;
                  var email     = user.email;

                  console.log("=== USER INFOS ===");
                  console.log("Gender : " + gender);
                  console.log("Birthday : " + birthday);
                  console.log("Name : " + name);
                  console.log("Email : " + email);

                  // => Open user session and redirect to the next page
              		this.navCtrl.push(this.questionPage);//I have to send data to this page

              });

          } 
          // An error occurred while loging-in
          else {

              console.log("An error occurred...");

          }

      })
      .catch((e) => {
          console.log('Error logging into Facebook', e);
      });
  }
  //My google login code start
  g_login(){
    if(this.platform.is('ios')){
      this.googlePlus.login({})
      .then(res => console.log(res))
      .catch(err => console.error(err));
    }else{
      this.googlePlus.login({
        'webClientId': '********-i5v3********tdj7gbmmkhj6s7vr.apps.googleusercontent.com'
      })
      .then(res => console.log(res))
      .catch(err => console.error(err));
    }
    
  }
//My google logini code End
  
}

Error Code 12500

follow bellow link to get the solution