When IPv4Only (IPv6Only) was used but the address could not be
interpreted as a IPv4 (IPv6) address, the error message referred
to the wrong IP version.

This also fixes up the error-checking logic so it's more precise
about what's being checked.

Fixes bug 13221; bugfix on 0.2.3.9-alpha

Signed-off-by: Kris Katterjohn <katterjohn@gmail.com>