findViewById returns unresolved reference


I am very disappointed since I bought this book version in order to get something reliable.
Now I feel cheated since the book has code I cannot run and had to change already.

// no lateinit etc.
// and later a direct call
true_button.setOnClickListener { view: View ->

It took me quite a while to find this since I am starting android but I hope this will help others.

Is there a ressource on outdated code updates?

Could you share your code i.e. MainActivity.kt?