Complete amateur setting high bars with first provider. How do I debug?

Having a hard time figuring out how to debug my code. Currently staring at the following:

fusion_vm.my-vm: Creating...
2020/03/10 22:11:46 [DEBUG] fusion_vm.my-vm: applying the planned Create change
2020/03/10 22:11:46 [DEBUG] fusion_vm.my-vm: apply errored, but we're indicating that via the Error pointer rather than returning it: status: 406, body: {
  "Code": 9,
  "Message": "Content type not supported"
}
2020/03/10 22:11:46 [ERROR] <root>: eval: *terraform.EvalApplyPost, err: status: 406, body: {
  "Code": 9,
  "Message": "Content type not supported"
}
2020/03/10 22:11:46 [ERROR] <root>: eval: *terraform.EvalSequence, err: status: 406, body: {
  "Code": 9,
  "Message": "Content type not supported"
}

Error: status: 406, body: {
  "Code": 9,
  "Message": "Content type not supported"
}

  on main.tf line 1, in resource "fusion_vm" "my-vm":
   1: resource "fusion_vm" "my-vm" {

Source: https://github.com/jovalle/terraform-provider-fusion

Wish I could print out the json generated to see what has gone awry at least. Any other pointers and resources will be much obliged!