Non skip pdf in lights HittableList

[niccolot]

Hello, if i add to the lights list an object that is not a metal or dielectric the image produced is like

i' ve obtained this by putting

// in the original main is glass
auto nonglass = make_shared<lambertian>(color(0.8, 0.2, 0.2));
world.add(make_shared<sphere>(point3(190,90,190), 90, nonglass));

// Light Sources
hittable_list lights;
auto m = shared_ptr<material>();
lights.add(make_shared<quad>(point3(343,554,332), vec3(-130,0,0), vec3(0,0,-105), m));
lights.add(make_shared<sphere>(point3(190, 90, 190), 90, m));

in the main.cpp of therestofyourlife part.

I may not have understood correctly this part of the code and thus it may not be an actual issue but still i wanted to ask this since also a material like a lambertian is still emitting some reflected light