fix: clear stale metadata extraction errors after successful retries

[CoralGarden52]

Related Issues

• fixes LLMMetadataExtractor retains failure metadata after a successful empty-JSON retry #12532

Proposed Changes

The failure metadata cleanup in LLMMetadataExtractor ran inside the loop over parsed metadata keys. A retry that returned a valid empty JSON object therefore left metadata_extraction_error and metadata_extraction_response on the successful document.

Move that cleanup after metadata is applied so every successful parse, including {}, clears stale failure state. The change includes synchronous and asynchronous regression tests for a failed extraction followed by an empty-JSON retry.

How did you test it?

• uvx hatch env run -e test -- pytest -q test/components/extractors/test_llm_metadata_extractor.py (29 passed, 2 skipped)
• uvx hatch run fmt-check haystack/components/extractors/llm_metadata_extractor.py test/components/extractors/test_llm_metadata_extractor.py
• uvx hatch -e test run types haystack/components/extractors/llm_metadata_extractor.py
• uvx hatch run reno lint .
• uvx hatch run pre-commit run --files haystack/components/extractors/llm_metadata_extractor.py test/components/extractors/test_llm_metadata_extractor.py releasenotes/notes/clear-stale-llm-metadata-retry-errors-778a9d314d7459d1.yaml

Notes for the reviewer

{} is valid when expected_keys is not configured and represents a successful extraction with no metadata to add. Public behavior and documentation remain unchanged, so no docstring update is needed.

This PR was fully generated with an AI assistant. I have reviewed the changes and run the relevant tests.

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have added unit tests.
• I have used a conventional commit title.
• I have documented the user-facing fix through a release note.
• I have run pre-commit hooks and fixed all issues.

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[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/components/extractors
llm_metadata_extractor.py
Project Total

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