attestations: AttributeError: 'tuple' object has no attribute 'replace'

[dimaqq]

Traceback (most recent call last):
  File "/app/attestations.py", line 149, in <module>
    main()
  File "/app/attestations.py", line 129, in main
    dist_to_attestation_map = compose_attestation_mapping(
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/attestations.py", line 103, in compose_attestation_mapping
    assert_attestations_do_not_pre_exist(dist_to_attestation_map)
  File "/app/attestations.py", line 88, in assert_attestations_do_not_pre_exist
    die(error_message)
  File "/app/attestations.py", line 45, in die
    msg = msg.replace('\n', '%0A')
          ^^^^^^^^^^^
AttributeError: 'tuple' object has no attribute 'replace'

I've no idea how it got to this, but I've hit this error in my CI:
https://github.com/dimaqq/otlp-test-data/actions/runs/13430069816/job/37519980376