What? You can return Exceptions instead of raising them. Since the language is dynamic, the caller can introspect.
Personally, from the perspective of a number parsing function, I think being passed an unparseable number counts as an "exceptional" situation- InvalidArgumentError- and I don't care which way it's returned- as an raised exception, or as an error object- as long as it's clearly documented, and the use matches the semantics of the function (NetworkNotAvailable is a better example of an exception where you're want to put something in the exception block)
Personally, from the perspective of a number parsing function, I think being passed an unparseable number counts as an "exceptional" situation- InvalidArgumentError- and I don't care which way it's returned- as an raised exception, or as an error object- as long as it's clearly documented, and the use matches the semantics of the function (NetworkNotAvailable is a better example of an exception where you're want to put something in the exception block)