When using GCE as a compute provider, spinning up a new instance results in;

Fog error: Invalid value for field 'resource.networkInterfaces[0].accessConfigs[0].natIP': 'false'.  Must be an IP address

which fails the provisioning of a new instance. The external IP address option on the "virtual machine" can be selected or unselected, both result in the same error.
This was also present in a previous version of fog but has since been fixed https://github.com/fog/fog/pull/2377

full error - http://fpaste.org/71294/05694951/

System Info:
GCE Instance - Debian GNU/Linux 7.3 (wheezy)
foreman 1.4.0-RC2 (including foreman-compute & foreman-gce)
puppet 3.4.2
fog (1.19.0)
google-api-client (0.7.1)
ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]