NullPointerException in Android Remote Config callback

Description

We are seeing a crash on Android when using countly_flutter Remote Config. The crash happens after calling remoteConfig.downloadAllKeys(...), when the native Android SDK finishes the remote config request and tries to notify Flutter through the plugin channel.

It looks like CountlyFlutterPlugin.notifyPublicChannelRCDL(...) calls publicChannel.invokeMethod(...) while publicChannel is null.

Package version

  countly_flutter: 26.1.0

Platform

• Flutter app
• Android
• Countly Flutter SDK 26.1.0

Usage

  Countly is initialized with config:

  final CountlyConfig config = CountlyConfig(
    serverUrl,
    appKey,
  )
    ..setRequiresConsent(true)
    ..setConsentEnabled([CountlyConsent.remoteConfig]);

  await Countly.initWithConfig(config);

Then Remote Config is fetched:

  await Countly.instance.remoteConfig.downloadAllKeys((
    RequestResult result,
    String? error,
    bool fullValueUpdate,
    Map<String, RCData> values,
  ) {
    // Handle downloaded values
  });

In our app this fetch is started asynchronously shortly after initialization.

Crash

  java.lang.NullPointerException: Attempt to invoke virtual method 'void io.flutter.plugin.common.MethodChannel.invokeMethod(java.lang.String,
  java.lang.Object)' on a null object reference
      at ly.count.dart.countly_flutter.CountlyFlutterPlugin.notifyPublicChannelRCDL(CountlyFlutterPlugin.java:88)
      at ly.count.dart.countly_flutter.CountlyFlutterPlugin$1.callback(CountlyFlutterPlugin.java:282)
      at ly.count.android.sdk.ModuleRemoteConfig.NotifyDownloadCallbacks(ModuleRemoteConfig.java:414)
      at ly.count.android.sdk.ModuleRemoteConfig.lambda$updateRemoteConfigValues$1$ly-count-android-sdk-ModuleRemoteConfig(ModuleRemoteConfig.java:110)
      at ly.count.android.sdk.ModuleRemoteConfig$$ExternalSyntheticLambda2.callback(D8$$SyntheticClass:0)
      at ly.count.android.sdk.ImmediateRequestMaker.onPostExecute(ImmediateRequestMaker.java:167)
      at ly.count.android.sdk.ImmediateRequestMaker.onPostExecute(ImmediateRequestMaker.java:16)
      at android.os.AsyncTask.finish(AsyncTask.java:771)
      at android.os.AsyncTask.access$900(AsyncTask.java:199)
      at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:788)
      at android.os.Handler.dispatchMessage(Handler.java:106)
      at android.os.Looper.loopOnce(Looper.java:226)
      at android.os.Looper.loop(Looper.java:313)
      at android.app.ActivityThread.main(ActivityThread.java:8663)
      at java.lang.reflect.Method.invoke(Method.java)
      at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:567)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)

Expected behavior

The plugin should not crash if the Flutter MethodChannel is unavailable. It should either skip the callback or guard the call with a null check.

Suspected cause

The public channel appears to be nullable in the Android plugin lifecycle, but notifyPublicChannelRCDL(...) invokes it without checking whether it has been initialized or is still attached.

A defensive check around publicChannel.invokeMethod(...) would likely prevent the crash.

Start at CountlyFlutterPlugin.notifyPublicChannelRCDL(...) and follow the callback from downloadAllKeys through the Android remote-config stack trace. Confirm the MethodChannel lifecycle around the callback, then verify that remote-config completion does not crash when the public channel is unavailable.