Adding a fallback param to utility functions

[Dalfons0]

I added to the utility functions an optional fallback function parameter so throwing an error can be avoided, anyway we will be maintaining the error throw as a default behaviour so we keep the functions backward compatible, and at the same time we are adding the flexibility to the user to decide what it's the behaviour when something it's missing (like returning undefined or a default value), as some times working with this in some projects (overall front end projects) could lead into undesirable consequences if not handled properly.

This also add the requested feature in the issue #88