[AlexXuz]

Summary

iter_tree_entries() and iter_tree_files() handle errors opening a directory and inspecting its entries, but an OSError raised while advancing an already-open os.scandir() iterator escapes without reaching on_error.

Handle scan-advancement errors using the existing contract: ignore the error when no handler is supplied, otherwise call the handler once with the original exception. Preserve entries already yielded and continue walking healthy sibling directories. Exceptions raised by the handler still propagate, and the scan context is closed.

The shared helper guards only next(entries), not entry processing or callback execution. The change history is updated in both its source and generated file.

Regression coverage

This is a synthetic directory-read-error reproduction, not a claim of a production incident. The tests inject an iterator that yields an entry and then raises OSError(EIO), plus a failing child scan alongside a healthy sibling.

Two new test methods cover both tree walkers, ignore/record/raise modes, original exception identity, once-only callbacks, context cleanup, partial results, and sibling traversal. Their eight subcases produce six errors and two failures against the unchanged base; all pass with the patch.

Validation

• python -m unittest discover -t . -s tests/: OK on Python 3.12.14 and 3.13.5, each reporting 292 tests and 786 skipped cases/subcases. Optional RE2/Hyperscan backends were not installed.
• Independent review and a separate full-suite run passed.
• Python 3.9 grammar parsing passed; this is not a Python 3.9 runtime test.
• git diff --check: passed.

Windows, other Python runtimes, optional native backends, type checking, and documentation builds were not run.

Prepared and reviewed with AI assistance; no human code review is claimed.