Digital Ocean Floating IP Assignments result in parsing error

[Brando753]

It appears that if you use digitalocean_floating_ip_assignment in your .tf file the terrafrom-inventory script will be unable to parse the resulting state file.

➜  git:(master) ✗ TF_STATE=. ./terraform-inventory --list                          
Error reading Terraform state: 0.12 format error: json: cannot unmarshal string into Go struct field resourceStateTerraform0dot12.index of type int; pre-0.12 format error: <nil> (nil error means no content/modules found in the respective format)

Removing the floating IP assignments and re-applying terraform results in the script working as expected.