App is crashing if link is resolved when flutter engine is not attached

[okmanideep]

Stacktrace

Fatal Exception: 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 com.singular.flutter_sdk.SingularSDK$1$1.run(SingularSDK.java:240)
       at android.os.Handler.handleCallback(Handler.java:938)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:233)
       at android.app.ActivityThread.main(ActivityThread.java:8068)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:631)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:978)

Observered in sdk version - 1.0.8

Potential Cause

A Runnable is being posted onto the UIThreadHandler when link is resolved. This could be unnecessary if the SingularLinkHandler.onResolved(linkParams) is invoked in the main thread and could be the root cause.

uiThreadHandler.post(new Runnable() {
  @Override
  public void run() {
    channel.invokeMethod("singularLinksHandlerName",linkParams); // NULL POINTER HERE!!! Due to NULL `channel`
  }
});

Potential Fix

If SingularLinkHandler.onResolved(linkParams) is expected to be only called in main thread and only after the flutter engine is attached, then we can just remove the uiThreadHandler.post() and directly invoke the method on the channel

If the link can be resolved from a background thread, Then we'll need to do two things:

• Check if the channel is not null before invoking channel.invokeMethod("singularLinksHandlerName",linkParams)
• If the channel is null, then queue this operation up and wait until the flutter engine is attached to invoke pending operations

[shefdanny]

thx @okmanideep for raising this issue. we will address it in our upcoming release.

[okmanideep]

No longer happening in the new SDK version 1.0.12.

Thank you 🙏