Book 2: Chapter 4, sequence issue with lambertian constructor

[silvercorked]

Book 2 chapter 4 section 2 concludes by passing a shared ptr of the newly created checker_texture class into to the make_shared function (Listing 25).

auto checker = make_shared<checker_texture>(0.32, color(.2, .3, .1), color(.9, .9, .9));
world.add(make_shared<sphere>(point3(0,-1000,0), 1000, make_shared<lambertian>(checker)));
// make_shared<lambertian>(checker) // lambertian has no constructor for shared_ptr<texture> by 4.2

An image is then shown, implying the code should be runnable. However, by this point, lambertian has no constructor that takes a shared_ptr. That constructor is introduced later in chapter 4, section 4 (Listing 30).

lambertian(shared_ptr<texture> a) : albedo(a) {}

It may be useful to introduce the constructor changes to the children of the material class before Listing 25, as walking through this awesome tutorial, I ended up having trouble here.