No way to get the error happening in HasNext

[matdurand]

Hi,

I would argue that the following line should return "true" (https://github.com/calvernaz/go-iterators/blob/master/iterator.go#L77)

My reasoning is that if it returns false, there is no way to tell if it's because there is no more element, or if there was an error. If it was to return true, then we would call .Next() to get the next and would receive (nil, someErr), which would allow us to deal with the err.

What do you think?