Promise with Ionic 3 is not working on some Android devices

I’m using Promise in my ionic function loadScript, and when I test on browser it’s OK, when I test on some devices android 4.x.x it’s OK, but when I test on my Lenovo K5 Note (Android 5.1),
the Promise doesn’t work and Exactly the debug alerts that my android 5.1 fired are:

alert('0');
alert('1');
alert('inside promise')
alert('return promise');

So it ignores the promise core instructions including:

alert('script loaded');

Below you will find the source code + ionic info

#Home.ts:


    //imports + Decorators
    export class HomePage {
      @ViewChild('map') mapElement: ElementRef;
      map: any;
    
      constructor(public navCtrl: NavController,
                  private platform:Platform,
                  private geolocation:Geolocation) {
      }
    
      ionViewDidLoad(){
        alert('0');
        this.loadScript()
        .then( () => {
          alert('initMap1');
          this.initMap();
          alert('initMap2');
        })
    
        .then( () => {
          console.log('geolocation');
          alert('geolocation')
          setTimeout(() => {
            this.getGeolocation();
          },5000);
          alert('geolocation end')
        })
    
        .then( () => {
          alert('end all');
          console.log('end all');
        })    
    
      }
    
      loadScript(){
        alert('1');
        var promise = new Promise((resolve, reject) => {
              alert("inside promise");
            console.log("Async Work Complete");
              console.log('start1');
              var script = document.createElement('script');
          
              script.src = "https://maps.googleapis.com/maps/api/js?key=AIzaSyBtYmf_L2ESZVcnkeIHRw_uD0VQIBbFYAM&libraries=places";
              console.log('append3');
              document.head.appendChild(script); //or something of the likes
              script.onload = function () {
                console.log('resolved');
                alert('loaded script');
                resolve();
              };  
        });
        alert('return promise');
        return promise;  
    
      }
    
      initMap() {
    //Implementation of initMap()
        alert('map Loaded');
      }
    
      getGeolocation(){
        //geoLocation implementation
      }
    
    }
    
    }

#ionic info


    cli packages: (/usr/lib/node_modules)
    
        @ionic/cli-utils  : 1.19.2
        ionic (Ionic CLI) : 3.20.0
    
    global packages:
    
        cordova (Cordova CLI) : 7.1.0 
    
    local packages:
    
        @ionic/app-scripts : 3.1.8
        Cordova Platforms  : android 6.3.0
        Ionic Framework    : ionic-angular 3.9.2
    
    System:
    
        Android SDK Tools : 26.1.1
        Node              : v8.9.4
        npm               : 5.7.1 
        OS                : Linux 4.13
    
    Environment Variables:
    
        ANDROID_HOME : xxx
    Misc:
    
        backend : pro
    cli packages: (/usr/lib/node_modules)
    
        @ionic/cli-utils  : 1.19.2
        ionic (Ionic CLI) : 3.20.0
    
    global packages:
    
        cordova (Cordova CLI) : 7.1.0 
    
    local packages:
    
        @ionic/app-scripts : 3.1.8
        Cordova Platforms  : android 6.3.0
        Ionic Framework    : ionic-angular 3.9.2
    
    System:
    
        Android SDK Tools : 26.1.1
        Node              : v8.9.4
        npm               : 5.7.1 
        OS                : Linux 4.13
    
    Environment Variables:
    
        ANDROID_HOME  : xxx/Sdk
    
    Misc:
    
        backend : pro

try a catch on the then. Likely the promise has an error not triggering the then

Before that, It ignores the promise core instructions including:
alert('script loaded');