Ionic 4- Cannot read property 'then' of undefined - Platform.ready()

Ionic Framework ionic-v3
1

Hello,

In Ionic I am trying to use Platform.ready() but I am getting the following error:

ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'then' of undefined
TypeError: Cannot read property 'then' of undefined
    at TeamComponent.<anonymous> (team.component.ts:25)
    at step (tslib.es6.js:97)
    at Object.next (tslib.es6.js:78)
    at tslib.es6.js:71
    at new ZoneAwarePromise (zone.js:910)
    at Module.__awaiter (tslib.es6.js:67)
    at team.component.ts:24
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (zone.js:391)
    at Object.onInvoke (core.js:17298)
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (zone.js:390)
    at resolvePromise (zone.js:831)
    at resolvePromise (zone.js:788)
    at zone.js:892
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:423)
    at Object.onInvokeTask (core.js:17289)
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:422)
    at Zone.push../node_modules/zone.js/dist/zone.js.Zone.runTask (zone.js:195)
    at drainMicroTaskQueue (zone.js:601)
    at ZoneTask.push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask [as invoke] (zone.js:502)
    at invokeTask (zone.js:1744)

import { Component, OnInit } from '@angular/core';
import { EmailComposer } from '@ionic-native/email-composer/ngx';
import { NavController, Platform, ToastController } from '@ionic/angular';

@Component({
  selector: 'team',
  templateUrl: './team.component.html',
  styleUrls: ['./team.component.scss'],
})
export class TeamComponent implements OnInit {

  constructor(
    private email: EmailComposer,
    private nav: NavController,
    private platform: Platform,
    private toast: ToastController
  ) { }

  ngOnInit() {}

  public openEmailApp(email: string) {
    this.platform.ready().then(() => {
      this.email.isAvailable().then(async (available: boolean) =>{
        if (available) {
          this.email.open({
            to: email
          });
        } else {
          let toast: any = await this.toast.create();
          await toast.present();
        }
       });
    });
  }

However, if I do a console log like this, it works and gives me ‘dom’ string: console.log(await this.platform.ready())

Whats the issue?

Thanks