How to fix 'ionic framework code push plugin'?

Question

Uncaught (in promise): TypeError: Object(...) is not a function TypeError: Object(...) is not a function at CodePush.sync (vendor.js:84065) at MyApp.webpackJsonp.406.MyApp.checkCodePush

I get the above error in my code. My code is as follows.

import { CodePush, InstallMode, SyncStatus } from '@ionic-native/code-push/ngx';
constructor(platform: Platform, statusBar: StatusBar, splashScreen: SplashScreen, private codePush: CodePush) {
platform.ready().then(() => {
  statusBar.styleDefault();
  splashScreen.hide();
  platform.ready().then(() => {
    statusBar.styleDefault();
    splashScreen.hide();
    this.codePush.sync();
  });
});