Check for nulls in state join condition

[awoehrl]

Please provide your name and company
NPG, Andreas Wöhrl

Link the issue/feature request which this PR is meant to address
#17

Detail what changes this PR introduces and how this addresses the issue/feature request linked above.

How did you validate the changes introduced within this PR?
Materialized the updated table and validated the sums for metrics that were off before.

Which warehouse did you use to develop these changes?
BigQuery

Did you update the CHANGELOG?

• Yes

Did you update the dbt_project.yml files with the version upgrade (please leverage standard semantic versioning)? (In both your main project and integration_tests)

• Yes

Provide an emoji that best describes your current mood

💃

Feedback

We are so excited you decided to contribute to the Fivetran community dbt package! We continue to work to improve the packages and would greatly appreciate your feedback on our existing dbt packages or what you'd like to see next.

PR Template

• Community Pull Request Template (default)

• Maintainer Pull Request Template (to be used by maintainers)

[fivetran-joemarkiewicz]

@awoehrl thanks for opening this PR! I was going to start taking a look at this. However, before I do so I was wondering if you had any issue with me making some commits directly to your branch? There are a few changes within our integration_tests folder and other maintenance changes we include for every release. If it works for you, as I review your changes I can make these background changes to your branch. This way we may fold them into the main branch more smoothly.

Let me know if you have any concerns!

[awoehrl]

Of course @fivetran-joemarkiewicz, you can go ahead with your changes directly on the branch. Let me know if you need me to change anything else!

[fivetran-joemarkiewicz]

@awoehrl thanks so much for identifying this issue and opening a PR to address it! We really appreciate your contribution and collaboration. I was able to recreate the error with our test data and confirm that your changes address the issue 🎉.

I made a few changes that are required before merging (nothing to adjust the sql logic) and with that this looks good to go! I will approve this PR and that will kick off our internal release process. You should see this live most likely before the end of the week 😄

[fivetran-catfritz]

Small suggestion for clarity but otherwise lgtm!