Error: gcp adv_peering_4fw_2spoke ilb ip_address default value

[Nornode]

Having a default value for the variable ip_address in ./modules/ilb/variables.tf casues errors:

terraform/gcp/adv_peering_4fw_2spoke (master) $ terraform apply
data.google_compute_zones.available: Refreshing state...

Error: could not parse "ip_address" to IP address

  on modules/ilb/main.tf line 23, in resource "google_compute_forwarding_rule" "default":
  23: resource "google_compute_forwarding_rule" "default" {



Error: could not parse "ip_address" to IP address

  on modules/ilb/main.tf line 23, in resource "google_compute_forwarding_rule" "default":
  23: resource "google_compute_forwarding_rule" "default" {

Yet, not having them casues other errors...