[Imkkey]

Summary

A dictionary-backed Choice currently raises raw TypeError for list, dict, or set configuration values. Besides losing the setting's name, this prevents OneOf from reaching a later valid collection template.

Normalize TypeError from the dict-dispatch lookup to ValueError, which the existing Choice.convert error handling turns into ConfigValueError. Keep the direct choices[value] lookup and leave the other converters unchanged.

Add regression coverage for rejected unhashable values, valid sequence/mapping fallbacks, nested mapping validation, and rejection when no fallback matches. Include compatibility controls for tuple/custom hashable keys, dict-subclass __missing__, and a custom lookup accepting lists. Verify that errors in sequence and enum converters still propagate directly and through OneOf. Add an unreleased changelog entry.

Validation

On Linux/Python 3.12.14:

• Before the fix: seven regression failures (three unhashable-value subtests plus four OneOf cases); compatibility controls pass.
• Afterward: 310 core tests and three subtests pass.
• Full suite: 311 tests and three subtests pass, with one pre-existing failure in test_bump_version_applies_sequential_changelog_updates. Unchanged upstream reproduces that same failure (300 tests pass): the expected changelog underline does not match the October date heading.
• Ruff lint and formatting, mypy targeting Python 3.10, strict Sphinx rebuild, changelog formatting/lint, and git diff --check pass.
• Separate YAML-loaded diagnostics: all 13 pass after the fix.

Prepared and tested with OpenAI Codex assistance. This is a draft for maintainer review.