using braces to limit scopes

limited-scope.js

const findUser () => {
  { 
    const userOrError = findUserInCache();
    if (userOrError instanceof Error) return userOrError;
    if (userOrError instanceof User) return userOrError;
  }
  { 
    const userOrError = findUserInDb();                   // reusing `userOrError` inside the same fn
    if (userOrError instanceof Error) return userOrError;
    if (userOrError instanceof User) return userOrError;
  }
  return new NoUser();
}