Plugin crash on Android.

I use flutter_downloader version 1.7.1. For some small number of users I observe the next crash:

Fatal Exception: java.lang.NullPointerException: Attempt to read from field 'java.lang.String io.flutter.view.FlutterCallbackInformation.callbackLibraryPath' on a null object reference
       at io.flutter.embedding.engine.dart.DartExecutor$DartCallback.toString(DartExecutor.java:22)
       at java.lang.String.valueOf(String.java:2896)
       at java.lang.StringBuilder.append(StringBuilder.java:132)
       at io.flutter.embedding.engine.dart.DartExecutor.executeDartCallback(DartExecutor.java:22)
       at vn.hunghd.flutterdownloader.DownloadWorker.startBackgroundIsolate(DownloadWorker.java:58)
       at vn.hunghd.flutterdownloader.DownloadWorker.access$000(DownloadWorker.java)
       at vn.hunghd.flutterdownloader.DownloadWorker$1.run(DownloadWorker.java:4)
       at android.os.Handler.handleCallback(Handler.java:873)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:214)
       at android.app.ActivityThread.main(ActivityThread.java:6986)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)

Crash happens in a second after launching the app.

[hnvn]

Released v1.7.2

[Taym95]

@Taym95 , could you provide more codes to handle the case that flutterCallback is null, because of without flutterCallback it can cause other issues.

if flutterCallback is null, I am quitting the function, this is the solution I see all other flutter plugin using it, I don’t see how to handle that case