ERROR : Inappropriate value for attribute "policy" : string required

Consul
,
1

I am getting the error - Inappropriate value for attribute “policy” : string required. Can you please help me.

main.tf

locals {
  vendor = toset(["vendor1","vendor2"])
}

data "template_file" "landing_policy_template" {
  template = file("landing_policy.json")
  for_each = local.vendor
   vars = {
     vendor = each.key
   }
}

resource "aws_iam_policy" "landing_policy" {
  for_each = toset(local.vendor)
  name = "vendor-${each.value}-policy"
  policy = "${data.template_file.landing_policy_template[each.value]}"
}

output "policy_op" {
  value = {
    for k, v in data.template_file.landing_policy_template : k => v
  } 
}

landing_policy.json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "ListingObjects",
            "Action": [
                "s3:ListBucket"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:s3:::test_bucket"
            ],
            "Condition": {
                "StringEquals": {
                    "s3:prefix": [
                        "${vendor}/"
                    ],
                    "s3:delimiter": [
                        "/"
                    ]
                }
            }
        }
    ]
}