FileChooser not giving File Browser on Android Emulator

Hi,
I am using FileChooser from ionic-native

I have just started my project, so there isn’t much code
But my file chooser is not giving even a file browser in my Android Emulator of Nexus 5X

This is my HTML file, which is binded to chooseFile event which has filechooser:

<ion-button (click)="chooseFile()">
  Choose file
</ion-button>

Inside my TS file, the chooseFile is defined as:

chooseFile(){
this.fileChooser.open()
      .then(uri => alert(uri))
      .catch(e => alert(e));
  }

Which produces the result as shown:

When the button is clicked it produces such an Alert message:

Is there anything I did wrong?

I am using Android Oreo version (8.1) on emulator of Nexus 5X

The project is built using Ionic framework 4.12.0 and Cordova 8.1.2 (cordova-lib@8.1.1)
with the command $ionic cordova run android -l

I am very sorry,
it seemed like I was careless enough that although the code in my application was automatically updated,
but I ran it by putting the apk into the emulator,
which happened before the installation of the packages.
This may have resulted in cordova packages which are used in the app not being found.
After reimporting the apk, the application works just fine