Allow return for skip void methods / closures

[PalumboN]

Now this produce an error (Here is tested with closures, but you have the same behavior for methods)

[fdodino]

Hi @PalumboN, I think it is a feature hahaha, but I've never felt necessary to go with this kind of constructions. The only thing is to use validation, and throwing an error is allowed. What do you think @npasserini?