Tolerate missing thumbnails when parsing playlist items

[MarvinSchenkel]

parse_playlist reads the thumbnail with nav(data, THUMBNAIL_RENDERER) and no none_if_absent. Some library shelf cards return a thumbnail renderer with an empty thumbnail object. nav then raises:

KeyError: "Unable to find 'thumbnails' using path ['thumbnailRenderer', 'musicThumbnailRenderer', 'thumbnail', 'thumbnails'] on {}, exception: 'thumbnails'"

parse_content_list has no per-item error handling, so one such card makes the whole get_library_playlists() call fail. The user gets no playlists at all.

The title field in the same function already guards against this case. parse_video and parse_related_artist in the same module also read the thumbnail with none_if_absent.

Reported downstream at music-assistant/support#6011.

Changes

• parse_playlist returns thumbnails: None instead of raising when the thumbnail is absent or empty.
• Added tests/parsers/test_browsing.py covering the four shapes: no renderer, empty renderer, empty music renderer, and empty thumbnail object.

[Copilot]

Pull request overview

This PR makes parse_playlist resilient to playlist items whose thumbnail renderer exists but contains an empty/missing thumbnail.thumbnails payload, preventing a single malformed card from causing get_library_playlists() to fail entirely.

Changes:

• Update parse_playlist to call nav(..., none_if_absent=True) for playlist thumbnails so missing/empty thumbnail structures yield thumbnails: None instead of raising.
• Add parser tests covering valid thumbnails and four “missing/empty thumbnail” renderer shapes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
ytmusicapi/parsers/browsing.py	Makes playlist thumbnail parsing tolerant of absent/empty thumbnail payloads by allowing nav to return None.
tests/parsers/test_browsing.py	Adds coverage for valid thumbnails plus multiple missing/empty thumbnail renderer shapes to prevent regressions.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.77%. Comparing base (72d47b3) to head (bdde0a6).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #974   +/-   ##
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  Coverage   95.77%   95.77%           
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  Files          47       47           
  Lines        2723     2723           
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  Hits         2608     2608           
  Misses        115      115           

Flag	Coverage Δ
unittests	95.77% <ø> (ø)

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