Remove duplicate "validationError" function

[mariusschulz]

I noticed that the validationError function is declared twice:

function validationError() {
  return new Error('Array Methods must be provided an Array');
}

function validationError() {
  return new Error('Array Methods must be provided an Array');
};

This PR removes one of the two function declarations.

[stefanpenner]

thanks!

[mariusschulz]

Thank you for the quick merge :)

[stefanpenner]

Thank you for the quick merge :)

Thanks for catching!