[Bug] infer_primary_key returns an array with None values if a node's unique or unique_combination_of_columns data test is misconfigured

[MichelleArk]

Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

Given a test configured on a model as:

- name: model
  tests:
    - dbt_utils.unique_combination_of_columns:
        combination_of_columns:
          - null

the inferred primary_key on model will result in [null], which violates the manifest schema and may lead to parsing issues down the road: https://schemas.getdbt.com/dbt/manifest/v12/index.html#nodes_additionalProperties_anyOf_i4_primary_key

Expected Behavior

Ideally, dbt-utils can raise a parse-time error. dbt-core itself isn't in a position to validate these contracts though.

In dbt-core it'd be better to return None or an empty list for primary_key instead of an invalid [null] array. dbt-core can also emit a warning log indicating the primary_key could not be inferred for a given model, even though it has a unique_combination_of_columns test.

Steps To Reproduce

in current behaviour.

Relevant log output

No response

Environment

No response

Which database adapter are you using with dbt?

No response

Additional Context

No response