VM: ensuring we nil-check items prior to accessing

[tombuildsstuff]

Fixes #2359 - also adds a bunch of extra nil-checking where it made sense on the initial pass-through

Since we'll be doing some work in this area for 2.0 - this is a quick cleanup whilst passing through.

[WodansSon]

@tombuildsstuff thanks for the PR, this is great and mostly LGTM left a couple of questions in the PR. Let me know what you think. Thanks!

[WodansSon]

@tombuildsstuff the build failed with 3 test failures, but I don't think they had anything to do with your code changes, looked more like issues inside of azure to me. I will leave it to you to decide what to do here. Thanks.

[tombuildsstuff]

Ignoring a few transitory test failures the tests pass:

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. If you feel I made an error 🤖 🙉 , please reach out to my human friends 👉 hashibot-feedback@hashicorp.com. Thanks!