TypeError: Cannot set property 'phone' of undefined at Object. I dont know what's wrong in my code

class Pet { constructor(animal, age, breed, sound) { this.animal = animal; this.age = age; this.breed = breed; this.sound = sound;

} get activity() { const today = new Date(); const hour = today.getHours();

if (hour < 8 && hour < 19) {
  return 'Playing';

} else { return 'sleeping'; } } get owner() { return this._owner; } set owner(owner) { this._owmer = owner; console.log(setter called ${owner}); }

speak() { console.log(this.sound); } }

class Owner { constructor(name, address) { this.name = name; this.address = address; }

set phone(phone) { const phoneNormalized = phone.replace(/[^0-9]/g, ''); this._phone = phoneNormalized; }

get phone() { return this._phone; }

}

const ernie = new Pet('dog', 1, 'pug', 'yip yip'); const vera = new Pet('dog', 8, 'border collie', 'woof woof');

ernie.owner = new Owner('Ashley', '123 Main Street'); ernie.owner.phone = '(555) 555-5555';

console.log(ernie.phone);