fix: skip None query input in QueryExpander

[MohammadHijjawi97]

Related Issues

No existing issue. This PR includes a regression test for the crash.

Proposed Changes:

Proposed Changes:

QueryExpander.run called query.strip() before checking the type. A None query from a pipeline raised AttributeError. Return an empty query list for None or non-string input, matching the existing empty-string warning path.

How did you test it?

Added unit tests for None query with and without include_original_query. Existing empty/whitespace tests still pass.

Notes for the reviewer

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 and updated the docstrings.
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I have documented my code.
• I have added a release note file, following the contributors guidelines.
• I have run pre-commit hooks and fixed any issue.

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[github-actions]

Hi @MohammadHijjawi97, thanks for your interest in contributing to Haystack! 🙏

⚠️ You currently have 5 open pull requests in this repository (#12794, #12793, #12792, #12790 and this one). Our review capacity is limited, so please hold off opening more PRs until we've had a chance to review your first 2 open PRs. This helps us give each contribution the attention it deserves. Thank you!

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[HaystackBot]

Hi @MohammadHijjawi97, thanks a lot for your contribution! 🙏

We noticed that the Contributor License Agreement (CLA) check (license/cla) hasn't passed yet, so we've temporarily moved this PR to draft and paused the review assignment.

To get your PR reviewed, please sign the CLA via the link in the license/cla check below (or in the CLA bot comment). As soon as the check turns green, this PR will automatically be marked ready for review again and a reviewer will be re-assigned.

[HaystackBot]

Thanks for signing the CLA, @MohammadHijjawi97! 🎉 This PR is now ready for review again and the reviewer has been re-assigned.

[MohammadHijjawi97]

CLA is signed now. This is ready for review whenever you have time.

[davidsbatista]

I will review this at the appropriate time, but I kindly ask you to respect the warnings regarding the number of PRs open and not open more PRs until what you already have open is reviewed.

Not doing so will result in a permanent ban.

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Project	Deployment	Actions	Updated
haystack-docs	Ready	Preview	Sep 22, 2026 10:02am UTC

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/components/query
query_expander.py					272-273
Project Total

This report was generated by python-coverage-comment-action