fix(misconf): do not erase variable type for child modules

[nikpivkin]

Description

Example config:

module "aws-rds" {
  source         = "terraform-aws-modules/rds/aws"
  version        = "~> 6.10.0"
  identifier     = "mydb"
  engine         = "postgres"
  family         = "postgres13"
  instance_class = "db.t4g.medium"
}

Before:

trivy conf -d . > log1.txt 2>&1
cat log1.txt |grep "Failed to expand"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.restore_to_point_in_time" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.s3_import" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.restore_to_point_in_time" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.s3_import" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.restore_to_point_in_time" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.s3_import" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.restore_to_point_in_time" value="cty.NilVal"
2024-11-18T20:36:26+06:00       ERROR   [terraform evaluator] Failed to expand block. Invalid "for-each" argument. Must be known and iterable.  block="module.aws-rds.module.db_instance.dynamic.s3_import" value="cty.NilVal"

After:

cat log2.txt |grep "Failed to expand"

Related issues

• Close https://github.com/aquasecurity/trivy/issues/7936

Checklist

• [x] I've read the guidelines for contributing to this repository.
• [x] I've followed the conventions in the PR title.
• [x] I've added tests that prove my fix is effective or that my feature works.
• [ ] I've updated the documentation with the relevant information (if needed).
• [ ] I've added usage information (if the PR introduces new options)
• [ ] I've included a "before" and "after" example to the description (if the PR is a user interface change).