How to get the value from another module

Hi,
in my whitelist folder, I have

whitelist-map.tf 
locals {
   whitelist = {
    dev  : [
      "dev-az-west1-test.com:443",
      "dev-az-west2-test.com:443",
      "dev-gcp-west1-test.io:443",
    ],
     qa = [
       "qa-az-west1-test.com:443",
       "qa-az-west1-test.com:443",
       "qa-gcp-west1-test.io:443",
     ],
}

outputs.tf
output "whitelist_output" {
  value       = local.whitelist[var.environment]
  description = "Map of <env>:<whitelist>"
}

variables.tf 
variable "environment" {
  description = "Environment (`dev`, `qa`)."
  type        = string
  validation {
    condition     = contains(["dev","qa"], var.environment)
    error_message = "Invalid environment. Valid environments: `dev`, and `qa`."
  }
}

in my another folder gcp I have cluster.tf

module "deployment_whitelists" {
  source = "../whitelists"
  environment = var.environment
}

module "deployment" {
  source                   = "../deployment"
  environment              = var.environment
  settings =  {"remote.whitelist" = module.deployment_whitelists.whitelist_output[var.environment]}
  }
}

the plan output is:

Error: Invalid index
│
│   on ../../modules/cluster.tf line 62, in module "deployment":
│   62:   settings =  {"remote.whitelist" = module.whitelists.whitelist_output[var.environment]}
│     ├────────────────
│     │ module.whitelists.whitelist_output is tuple with 3 elements
│     │ var.environment is "dev"
│
│ The given key does not identify an element in this collection value: a number is required.

What I want to get is ( for dev environment in this case):
settings = {“remote.whitelist”= [
dev-az-west1-test.com:443”,
dev-az-west2-test.com:443”,
dev-gcp-west1-test.io:443”,
]}

Since gcp module wants to use the data map defined in whitelist module. so, I thought i can use outputs.tf to output this map data.
But it always gives me error. I tried different ways, the error is always like this.
I suspect that the way I was trying to get the value from output.tf is incorrect. Not quite sure what is wrong.

terraform.state seems cannot be used since these two folders are modules. the actual plan is in the another folder (with version.tf in it).

Could someone point out the root cause of error? Thank you very much in advance.

William

Hi I figured it out. in the output.tf, variable environment has been used. In the calling module, it should not be used again.