Fregot json unmarshaling behaves differently than unmarshling in OPA.

[Bard]

When I run the command fregot test lib rules tests/rules I get the error below.

fregot (eval error):
  "rules\tf\aws\s3\bucket_policy.rego" (line 17, column 12):
  builtin error:

    17| policy :=  json.unmarshal(input.policy)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  Expected string but got null

  Stack trace:
    rule rules.tf_aws_s3_bucket_policy.policy at rules\tf\aws\s3\bucket_policy.rego:22:13
    rule rules.tf_aws_s3_bucket_policy.transport_policy at rules\tf\aws\s3\bucket_policy.rego:40:3
    rule rules.tf_aws_s3_bucket_policy.allow at tests/rules\tf\aws\s3\bucket_ssl_test.rego:20:7
    rule rules.tf_aws_s3_bucket_policy.test_s3_bucket_sse at tests:1:1

Line 17 of bucket_policy.rego looks like: policy := json.unmarshal(input.policy)

When I run the OPA version of the command above my test pass okay:

opa test .\tests\rules\tf\aws\s3 .\rules\ .\lib\
PASS: 2/2`

In case you need it, the structure of input is below.

= {
  "id": "aws_s3_bucket.no_policy",
  "acl": "private",
  "_provider": "aws",
  "website": [],
  "replication_configuration": [],
  "cors_rule": [],
  "tags": null,
  "bucket_prefix": null,
  "policy": null,
  "server_side_encryption_configuration": [],
  "grant": [],
  "object_lock_configuration": [],
  "logging": [],
  "lifecycle_rule": [],
  "_type": "aws_s3_bucket",
  "force_destroy": true
}

Policy will either be null or contain a string of JSON.

I'm running version fregot v0.13.4