Había pasado por SO preguntas por aquí. Pero no puedo obtener lo que este error intenta sugerir. Por favor, ayúdame con esto.

Por último, MÓDULO SUPERIOR Significa qué módulo. Como soy nuevo en esto, es por eso que no entiendo esto correctamente.

Mi código:

app.module.ts

   @NgModule({
  declarations: [
    MyApp,
    UsersPage,
    ReposPage,
    OrganisationsPage,
    UserDetailsPage,
    LoginPage

  ],
  imports: [

    BrowserModule,
    HttpModule,
    IonicModule.forRoot(MyApp),

  ],
  bootstrap: [IonicApp],
  entryComponents: [
    MyApp,
    LoginPage,
    UsersPage,
    ReposPage,
    OrganisationsPage,
    UserDetailsPage,


  ],

Login.module.ts

import { NgModule } from '@angular/core';
import { IonicPageModule,IonicPage } from 'ionic-angular';
import { LoginPage } from './login';
//import { IonicPage } from 'ionic-angular';

@IonicPage()
@NgModule({
  declarations: [
    LoginPage,
  ],
  imports: [
    IonicPageModule.forChild(LoginPage),
  ],
  entryComponents: [
    LoginPage
  ],
  exports: [
    LoginPage
  ]
})
export class LoginPageModule {}

CÓDIGO ACTUALIZADO SEGÚN SU COMENTARIO

app.module.ts

import { Component } from '@angular/core';
import { NavController, AlertController, LoadingController, Loading, IonicPage } from 'ionic-angular';
import { AuthService } from '../../providers/auth-service';


@IonicPage()
@Component({
  selector: 'page-login',
  templateUrl: 'login.html',
})
export class LoginPage {
  loading: Loading;
  registerCredentials = { email: '', password: '' };

  constructor(private nav: NavController, private auth: AuthService, private alertCtrl: AlertController, private loadingCtrl: LoadingController) { }

  public createAccount() {
    this.nav.push('RegisterPage');
  }

  public login() {
    this.showLoading()
    this.auth.login(this.registerCredentials).subscribe(allowed => {
      console.log(allowed)
      if (allowed) {        
        this.nav.setRoot('HomePage');
      } else {
        this.showError("Access Denied");
      }
    },
      error => {
        this.showError(error);
      });
  }

  showLoading() {
    this.loading = this.loadingCtrl.create({
      content: 'Please wait...',
      dismissOnPageChange: true
    });
    this.loading.present();
  }

  showError(text) {
    this.loading.dismiss();

    let alert = this.alertCtrl.create({
      title: 'Fail',
      subTitle: text,
      buttons: ['OK']
    });
    alert.present(prompt);
  }
}

login.module.ts

import { NgModule } from '@angular/core';
import { IonicPageModule,IonicPage } from 'ionic-angular';
import { LoginPage } from './login';
//import { IonicPage } from 'ionic-angular';


@NgModule({
  declarations: [
    LoginPage,
  ],
  imports: [
    IonicPageModule.forChild(LoginPage),
  ],
  entryComponents: [
    LoginPage
  ],
  exports: [
    LoginPage
  ]
})
export class LoginPageModule {}

login.ts

import { Component } from '@angular/core';
import { NavController, AlertController, LoadingController, Loading, IonicPage } from 'ionic-angular';
import { AuthService } from '../../providers/auth-service';


@IonicPage()
@Component({
  selector: 'page-login',
  templateUrl: 'login.html',
})
export class LoginPage {
  loading: Loading;
  registerCredentials = { email: '', password: '' };

  constructor(private nav: NavController, private auth: AuthService, private alertCtrl: AlertController, private loadingCtrl: LoadingController) { }

  public createAccount() {
    this.nav.push('RegisterPage');
  }

  public login() {
    this.showLoading()
    this.auth.login(this.registerCredentials).subscribe(allowed => {
      console.log(allowed)
      if (allowed) {        
        this.nav.setRoot('HomePage');
      } else {
        this.showError("Access Denied");
      }
    },
      error => {
        this.showError(error);
      });
  }

  showLoading() {
    this.loading = this.loadingCtrl.create({
      content: 'Please wait...',
      dismissOnPageChange: true
    });
    this.loading.present();
  }

  showError(text) {
    this.loading.dismiss();

    let alert = this.alertCtrl.create({
      title: 'Fail',
      subTitle: text,
      buttons: ['OK']
    });
    alert.present(prompt);
  }
}