[mewpmewp2]

  function areAllTheirHatsGreen(someone) {
      return someone.getHats().every(hat => hat.color === 'green')
  }

I wonder if there's a language or programming paradigm where this function wouldn't be determined simlarly.

I think best you could do is make a validation check that throws an error if there's no hats at all, but would that make sense?

What if you have a function that has to return a boolean and not throw an error.

[MrMcCall]

The best I've found are languages like F# that allow you to return a pair of values, which for your example would be a tuple of (bool, bool), where the first is isError and the second is the evalResult. Of course, you better not mix `em up!

As to paradigms, I've not seen anything yet, but I haven't seen it all, and corporate America has their legacy systems that limit their explorations.