Fix reply already submitted

[kreativityapps]

This fixes IllegalStateException: Reply already submitted, the crash occurs often on Android.

Fatal Exception: java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=3548984, result=0, data=null} to activity {com.app.this/com.app.this.MainActivity}: java.lang.IllegalStateException: Reply already submitted
       at android.app.ActivityThread.deliverResults(ActivityThread.java:5555)
       at android.app.ActivityThread.handleSendResult(ActivityThread.java:5596)
       at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
       at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
       at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2326)
       at android.os.Handler.dispatchMessage(Handler.java:106)
       at android.os.Looper.loop(Looper.java:246)
       at android.app.ActivityThread.main(ActivityThread.java:8570)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)

Caused by java.lang.IllegalStateException: Reply already submitted
       at io.flutter.embedding.engine.dart.DartMessenger$Reply.reply(DartMessenger.java:431)
       at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler$1.success(MethodChannel.java:272)
       at biz.cunning.cunning_document_scanner.CunningDocumentScannerPlugin.addActivityResultListener$lambda$3(CunningDocumentScannerPlugin.kt:102)
       at io.flutter.embedding.engine.FlutterEngineConnectionRegistry$FlutterEngineActivityPluginBinding.onActivityResult(FlutterEngineConnectionRegistry.java:774)
       at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.onActivityResult(FlutterEngineConnectionRegistry.java:422)
       at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onActivityResult(FlutterActivityAndFragmentDelegate.java:857)
       at io.flutter.embedding.android.FlutterActivity.onActivityResult(FlutterActivity.java:884)
       at android.app.Activity.dispatchActivityResult(Activity.java:8541)
       at android.app.ActivityThread.deliverResults(ActivityThread.java:5548)
       at android.app.ActivityThread.handleSendResult(ActivityThread.java:5596)
       at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
       at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
       at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2326)
       at android.os.Handler.dispatchMessage(Handler.java:106)
       at android.os.Looper.loop(Looper.java:246)
       at android.app.ActivityThread.main(ActivityThread.java:8570)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)

[vicajilau]

Thank you very much for the pull request!