Fix reverse on empty openArray (#5407)
Fix reverse on empty openArray (#5407)

Reversing an empty `openArray` would raise a RangeError. For instance for `a: seq[int] = @[]`, we have `a.high` return `-1` but `-1` is not a `Natural`. Leaving the array as-is is the expected behaviour.
dom96/Nim,dom96/Nim,russpowers/Nim,dom96/Nim,tulayang/Nim,tulayang/Nim,dom96/Nim,russpowers/Nim,russpowers/Nim,tulayang/Nim,tulayang/Nim,russpowers/Nim,russpowers/Nim,dom96/Nim,russpowers/Nim,dom96/Nim,dom96/Nim,tulayang/Nim,tulayang/Nim,russpowers/Nim