Device Rotation crash in QuizActivity

While testing the rotation of the device (in the emulator - Android Studio 3.5 on Mac), the QuitActivity app crashes in FragmentManagerImpl.moveToState. I did try the version BNR provides as a download and it work as expected. I am guessing that the problem has something to do with the version difference between my Studio install and what was used for the book or the Android OS version. I have tried to set the min/max/target SDK in the manifest, but that does not seem to help.

I just cleaned up some build warnings and found that removing the casting of the Buttons in the onCreate seemed to address the crash.