F merge missing list datatype

Summary

For #151 (closed). Does not fix the actual problem because this is a CloseWon't Fix (or has to be fixed in the crawler) but raises a better error message instead.

Focus

Check that the correct error message is shown.

Test Environment

Unit tests should be sufficient.

Check List for the Author

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• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

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