zombies.push(Zombie(_name, _dna)) — 1

[veridelisi]

DON’T USE THIS
uint id = zombies.push(Zombie(_name, _dna)) — 1;
gives error in remix

USE THIS
zombies.push(Zombie(_name, _dna));
uint id = zombies.length - 1;

sincerely
Dr. Engin YILMAZ

[felixhalim]

Agree, .push() no longer have a return value in solidity version (0.8.14)

Reference: https://docs.soliditylang.org/en/v0.8.14/types.html?highlight=push#arrays