Node Count - list

Ho 3 liste (nodo Count)
lista nr.1 —> otto elementi ----> Count=8 (rosso)
lista nr.2 —> sei elementi ----> Count=6 (verde)

lista nr.3 —> zero elementi ----> Count=1 (blu) —> perchè ??? —> giusto è Count=0

Your Python node produces an empty list.
From that you’re taking the first item - which doesn’t work, so you get null instead.
And null counts as 1, not as 0.