错误：未捕获（在承诺中）：导航堆栈至少需要一个根页面

Question

我遇到了保存数据的问题。它说

运行时错误：未捕获（在承诺中）：导航堆栈至少需要一个根页

这是我的app.component.ts

import { Component, ViewChild } from '@angular/core';
import { Platform, NavController, MenuController } from 'ionic-angular';
import { StatusBar } from '@ionic-native/status-bar';
import { SplashScreen } from '@ionic-native/splash-screen';
import firebase from 'firebase';

//import { SearchPage } from '../pages/search/search';
import { AppointmentPage } from '../pages/appointment/appointment';
import { TabsPage } from '../pages/tabs/tabs';
import { AuthServices } from '../provider/auth.service';
import { LoginPage } from '../pages/login/login';
import { SignUpPage } from '../pages/sign-up/sign-up';


@Component({
  templateUrl: 'app.html'
})
export class MyApp {
  rootPage:any = TabsPage;
  AppointmentPage: AppointmentPage;
  LoginPage =LoginPage;
  SignUpPage = SignUpPage;
  isAuthenticated = false;

@ViewChild('nav') nav: NavController;

  constructor(platform: Platform, statusBar: StatusBar, splashScreen: SplashScreen, 
              private authService: AuthServices,
              private menuCtrl: MenuController,) {
    firebase.initializeApp({
    apiKey: "AIzaSyCearIrLYBjHJCq46MOXAlw-fnmm5loS6U",
    authDomain: "mydatalogin-3ed97.firebaseapp.com",
    });

    firebase.auth().onAuthStateChanged(user => {
      if (user){
        this.isAuthenticated = true;
        this.nav.setRoot(this.rootPage);
      }
      else{
        this.isAuthenticated = false;
        this.nav.setRoot(this.LoginPage);
      }
    });

    platform.ready().then(() => {
      // Okay, so the platform is ready and our plugins are available.
      // Here you can do any higher level native things you might need.
      statusBar.styleDefault();
      splashScreen.hide();
    });
  }
    onLoad(page: any){
    this.nav.setRoot(page);
    this.menuCtrl.close();
  }

  onLogout(){
    this.authService.onLogout();
    this.menuCtrl.close();
  }
}

这是form.ts

import { Component } from '@angular/core';
import {  NavController, ViewController } from 'ionic-angular';

@Component({
  selector: 'page-appointment',
  templateUrl: 'appointment.html',
})
export class AppointmentPage {
  fname: string;
  pno: string;
  today: Date;
  time: string;
  boutique: string;
  planner: string;
  halls: string;
  catering: string;
  services: string;
  message: string;

  constructor(public navCtrl: NavController, public view: ViewController) {
  }

saveItem(){

    let newItem = {
      boutique: this.boutique,
      planner: this.planner,
      halls: this.halls,
      catering: this.catering,
      services: this.services,

      today: this.today,
      fname: this.fname,
      pno: this.pno,
      time: this.time,
      message: this.message,

        }
   console.log('saved item: ', newItem);
    this.view.dismiss(newItem);
  }

    }

我尝试刷新所有文件和浏览器，但它仍然无法保存数据。我只使用firebase登录和保存我使用离子存储的数据..