bug:NullPointerException on BarcodeScanner.startScan after updating to ionic 8/plugin v8

[mojontwins]

Plugin(s)

• Barcode Scanning
• Face Detection
• Face Mesh Detection
• Selfie Segmentation
• Subject Segmentation
• Translation

Version

8.0.1

Platform(s)

• Android
• iOS
• Web

Current behavior

I've been maintaining a ionic-capacitor based app that uses MLkit Barcode Scanner. I've recently updated the app to Ionic 8, and the plugin to v8.0.1, and now I get a NullPointerException when I try to start a new scan.

  E  Attempt to invoke virtual method 'void androidx.camera.view.PreviewView.setScaleType(androidx.camera.view.PreviewView$ScaleType)' on a null object reference
     java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.camera.view.PreviewView.setScaleType(androidx.camera.view.PreviewView$ScaleType)' on a null object reference
     	at io.capawesome.capacitorjs.plugins.mlkit.barcodescanning.BarcodeScanner.lambda$startScan$0(BarcodeScanner.java:106)
     	at io.capawesome.capacitorjs.plugins.mlkit.barcodescanning.BarcodeScanner.$r8$lambda$zbIUX_mdGY-ehC6dJnja9lN0-xQ(Unknown Source:0)
     	at io.capawesome.capacitorjs.plugins.mlkit.barcodescanning.BarcodeScanner$$ExternalSyntheticLambda6.run(D8$$SyntheticClass:0)
     	at android.os.Handler.handleCallback(Handler.java:907)
     	at android.os.Handler.dispatchMessage(Handler.java:105)
     	at android.os.Looper.loop(Looper.java:216)
     	at android.app.ActivityThread.main(ActivityThread.java:7625)
     	at java.lang.reflect.Method.invoke(Native Method)
     	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)
     	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:987)

This is the relevant code

  async scanSingleBarcode() {
    return new Promise<Barcode> (async resolve => {
      document.querySelector('body')?.classList.add('barcode-scanner-active');

      const listener = await BarcodeScanner.addListener(
        'barcodesScanned',
        async result => {
          await listener.remove();
          document
            .querySelector('body')?.classList.remove('barcode-scanner-active');
          await BarcodeScanner.stopScan();
          resolve(result.barcodes[0]);
        },
      );

      await BarcodeScanner.startScan();
    });
  };

BTW the example in README.md seems outdated as the listener should be barcodesScanned as opposed to barcodeScanned.

Expected behavior

Camera opens and scans a QR, no NullPointerException

Reproduction

https://github.com/mojontwins/minimalcam

Steps to reproduce

• ionic capacitor build android,
• launch from Android Studio and run on device,
• Press "Scan QR" button.

Other information

No response

Capacitor doctor

$ npx cap doctor
   Capacitor Doctor

Latest Dependencies:

  @capacitor/cli: 8.2.0
  @capacitor/core: 8.2.0
  @capacitor/android: 8.2.0
  @capacitor/ios: 8.2.0

Installed Dependencies:

  @capacitor/android: 8.2.0
  @capacitor/ios: 8.2.0
  @capacitor/cli: 8.2.0
  @capacitor/core: 8.2.0

[success] Android looking great! �
[error] Xcode is not installed

Before submitting

• I have read and followed the bug report guidelines.
• I have attached links to possibly related issues and discussions.
• I understand that incomplete issues (e.g. without reproduction) are closed.

[robingenz]

Closed as duplicate of #160. Feel free to create a PR in case it's an issue in the plugin and not just a configuration issue.

[mojontwins]

How is it a duplicate? I updated the plugin and the application stopped working, and I am not using Android Fragments.

[robingenz]

It’s a duplicate because a similar issue was already reported in #160. Besides that, we can’t debug the issue because your reproducible example doesn’t include the Android platform. As I said, feel free to create a PR.