I keep getting an error on the console when trying to run 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 <= 20) {
    return 'playing';  
} else {
  return 'sleeping';
  }
}

get owner() {
  return this._owner;
}

set owner(owner) {
  this._owner = 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.speak();
//vera.speak();


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

console.log(ernie);