@herbert

Good morning Herbert!

You already know this, as the downloadable code has corrected it already:

• On page 92, you define the enum GamePhase. This has a number of traits derived, but is missing the Copy trait. Without this, a rather cryptic error message results when running the code later in the chapter (specifically when modifying the build() function).
• The other change between the book code and the downloadable code: On p93, you add the gameStatePlugin:

  .add_plugins(GameStatePlugin::<GamePhase>::new( 
      GamePhase::MainMenu,
      // ...
  )
  

In the downloadable code, this call is just .add_plugin(GameStatePlugin::new(

I am not (yet) sure if this second change is an issue or not - I am going to go and play a bit to see what happens!