Previously, it was a publically accessible but invalid value (valueEmpty).
* Deprecate internal use of UndefinedValue(), NullValue(), FalseValue(), TrueValue()
* Guard against Empty, Result, Reference values from escaping the package
Basically, check that start is less than length before trying
to take a slice.
Also, rename valueToArrayIndex to valueToRangeIndex to reflect
the fact that it does not always return a value that is valid
index (value could be length)
