url_description_uniqueness_check fails with TypeError on specific metadata record

[rajeshpandey2053]

Describe the bug

When running the tests on the concept id C2068391958-LARC_ASDC using the pyQuARC master branch, the check fails with a TypeError, indicating that a NoneType was encountered where a string was expected.

To Reproduce

Steps to reproduce the behavior:

• Test using C2068391958-LARC_ASDC (umm-c)
• Run pyQuARC master branch on the record above
• See the pyQuARC errors for the above record
• Expected behavior
  "pyquarc_errors": [ { "message": "Running check for the rule: 'url_description_uniqueness_check' failed.", "details": "sequence item 0: expected str instance, NoneType found" } ]

Additional context

When briefly investigated, it seemed like there is an issue with the uniqueness_check function in custom_validator.py file.