Init AppsFlyer in a background process on Android device causes a NullPointerException

[Luvti]

Describe the bug Init AppsFlyer in a background process on Android device causes a NullPointerException

To Reproduce Steps to reproduce the behavior:

1. Use Firebase messaging for sending a push notification in the background process FirebaseMessaging.onBackgroundMessage(backgroundMessageHandler);
2. init AppsFlyer in background process (backgroundMessageHandler):

   appsflyerSdk = AppsflyerSdk(appsFlyerOptions);
   await appsflyerSdk.initSdk(
   registerConversionDataCallback: true,
   registerOnAppOpenAttributionCallback: true,
   registerOnDeepLinkingCallback: true,
   );

3. Error:

   E/MethodChannel#af-api: Failed to handle method call
   java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
       at com.appsflyer.AppsFlyerLibCore.start(:921)
       at com.appsflyer.AppsFlyerLibCore.start(:902)
       at com.appsflyer.AppsFlyerLibCore.start(:897)
       at com.appsflyer.appsflyersdk.AppsflyerSdkPlugin.initSdk(AppsflyerSdkPlugin.java:586)
       at com.appsflyer.appsflyersdk.AppsflyerSdkPlugin.onMethodCall(AppsflyerSdkPlugin.java:128)
       at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:233)
       at io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:85)
       at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:818)
       at android.os.MessageQueue.nativePollOnce(Native Method)
       at android.os.MessageQueue.next(MessageQueue.java:336)
       at android.os.Looper.loop(Looper.java:197)
       at android.app.ActivityThread.main(ActivityThread.java:8016)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1076)

Expected behavior No error.

[GM-appsflyer]

Hey @Luvti , Thanks for reaching out!

I've investigated a bit, and it seems because "_firebaseMessagingBackgroundHandler' runs in its own isolate outside your applications context" this is probably the reason this error appears. Please check this section on the firebase flutter docs: https://firebase.flutter.dev/docs/messaging/usage/#background-messages

What is your use case? Maybe we can find another way to tackle this.

[SkywalkerDarren]

I got the same issue when the application was in the background and then flutter activity was destroyed. Turn on 'Don't keep activities' in 'Developer options' can reproduce this.

E/MethodChannel#af-api: Failed to handle method call
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
        at com.appsflyer.AppsFlyerLibCore.start(:921)
        at com.appsflyer.AppsFlyerLibCore.start(:902)
        at com.appsflyer.AppsFlyerLibCore.start(:897)
        at com.appsflyer.appsflyersdk.AppsflyerSdkPlugin.initSdk(AppsflyerSdkPlugin.java:586)
        at com.appsflyer.appsflyersdk.AppsflyerSdkPlugin.onMethodCall(AppsflyerSdkPlugin.java:128)
        at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:233)
        at io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:85)
        at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:818)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:335)
        at android.os.Looper.loop(Looper.java:183)
        at android.app.ActivityThread.main(ActivityThread.java:7664)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

[felipe-xavier]

Hey, has anyone found a solution for this?