Check if test_metadata Exists First

[sungchun12]

When running with dbt Cloud artifacts, I came across the error below.

Running with data-diff=0.9.2
10:28:28 ERROR    'NoneType' object has no attribute 'name'                                                                                                                                                                                                 __main__.py:329
Traceback (most recent call last):
  File "/Users/sung/public-api-demos/venv/bin/data-diff", line 8, in <module>
    sys.exit(main())
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/data_diff/__main__.py", line 312, in main
    dbt_diff(
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/data_diff/dbt.py", line 83, in dbt_diff
    dbt_parser = DbtParser(profiles_dir_override, project_dir_override, state)
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/data_diff/dbt_parser.py", line 138, in __init__
    self.unique_columns = self.get_unique_columns()
  File "/Users/sung/public-api-demos/venv/lib/python3.9/site-packages/data_diff/dbt_parser.py", line 487, in get_unique_columns
    if node.test_metadata.name == "unique":
AttributeError: 'NoneType' object has no attribute 'name'

This happens because the get_unique_columns function assumes every node has a test_metadata attribute which is optional within dbt_config_validators.py. This checks the attribute first before proceeding with the rest of the logic.