In Scala, how to use `Nothing` as returned value to Fake a method?

I'd like to create a method called save and haven't been ready to implement it. However, I don't want it to throw exceptions during evaluated. So I tried to make it return a Nothing as the result.

def save[A <: AuthInfo](profile: CommonSocialProfile): Future[UserProfile] = {
  // To be done
  new Nothing()
}

But this won't work, the compiler says:

class Nothing is abstract; cannot be instantiated

I also tried ??? as a placeholder, but that will throw a NotImplementedError, which doesn't fit my needs either..

def save[A <: AuthInfo](profile: CommonSocialProfile): Future[UserProfile] = ???

Does anyone have easier ways about fake a method in Scala?