Android NullPointerException crash on minimalize of app


Hi, I have problem on some Android devices. When I close app by middle button app crashes with this log.
Phone is Samsung Galaxy J3(2016) (j3xnlte), 1536MB RAM, Android 5.1.

Using tns android 4.0.1

  at$1.onPreDraw (
  at android.view.ViewTreeObserver.dispatchOnPreDraw (
  at android.view.ViewRootImpl.performTraversals (
  at android.view.ViewRootImpl.doTraversal (
  at android.view.ViewRootImpl$ (
  at android.view.Choreographer$ (
  at android.view.Choreographer.doCallbacks (
  at android.view.Choreographer.doFrame (
  at android.view.Choreographer$ (
  at android.os.Handler.handleCallback (
  at android.os.Handler.dispatchMessage (
  at android.os.Looper.loop (
  at (
  at java.lang.reflect.Method.invoke (Native Method)
  at java.lang.reflect.Method.invoke (
  at$ (
  at (

java.lang.NullPointerException: Attempt to read from field 'int' on a null object reference