helper.transform_asg_style_tags() not protected when resource['values'] is None

[joaoubaldo]

Description

To Reproduce

The issue is a bit flaky. It doesn't look directly related with a specific resource (we are using terraform-compliance on a high number of cicd pipelines and this issue is only affecting a few of them)
Example: when generating a plan that applies the whole infrastructure from scratch it doesn't fail, however when the plan includes updates, terraform-compliance fails with the Exception:

        | Name | .+    |
          AttributeError: 'NoneType' object has no attribute 'get'

Feature File:
https://github.com/joaoubaldo/cli/blob/issue-567-handle-none-resource-values/tests/functional/test_issue-567/test.feature
Plan File:
https://github.com/joaoubaldo/cli/blob/issue-567-handle-none-resource-values/tests/functional/test_issue-567/plan.out.json

Used terraform-compliance Parameters:
I was able to isolate the issue by running radish directly with the parameters terraform-compliance uses.
bin/radish --write-steps-once /feature/directory/ --basedir /terraform_compliance/steps --user-data=plan_file=my-plan.tfplan.json --user-data=exit_on_failure=False --user-data=terraform_executable=None --user-data=no_failure=False --user-data=silence_mode_enabled=False --user-data=debugging_mode_enabled=False

Running via Docker:
No

Error Output:

        | Name | .+    |
          AttributeError: 'NoneType' object has no attribute 'get'

Expected Behavior:
Failed / passed scenarios without Exceptions.

Tested Versions:

• terraform-compliance version: 1.3.29
• terraform version: 1.0.2
• python version: 3.9.7

Additional Context:
From what I was able to debug I have found a potential issue here

cli/terraform_compliance/common/helper.py

Line 507 in 811d178

tag = resource.get('values', {}).get('tag')

)
When resource['values'] is None, the original Exception will be thrown.
I confirm that having a None protection here fixes my problem but I am not certain that having resource['values'] as None at this point means the issue should be fixed somewhere else first.

I'll create a PR and reference the issue.

[eerkunt]

Thanks a lot for the PR 🎉

Looks great.

[joaoubaldo]

Issue is fixed in master. cc @eerkunt