const user = {
  name: 'Sarah',
  profile: {
    settings: {
      theme: 'dark'
    }
  }
};

const config = {
  name: 'John',
  profile: null
};

console.log(user.profile?.settings?.theme);
console.log(config.profile?.settings?.theme);
console.log(user.profile?.preferences?.language);
console.log(config.profile?.settings?.theme ?? 'light');