Spawn error

[dobobaie]

Hi !

Can you add this code : .on('error', function(err) { callback(new Error(err)); });

After spawn function (line: 34 file: validator.js) because when spawn failed sometime exit event is not called and we can't debug without error event.

Thank you !

[nikku]

I'm not quite sure that I understand which scenario you're trying to support here. Under which circumstances does spawning fail?

Anyway, I'd accept a pull request regarding this change if you provide a test case with it.