fix: skip metadata source search when query and filters are empty

[Sanjays2402]

Description

Fixes #6862.

Items with no artist/title tags produce a search with an empty query and no filters. The request was still sent to the metadata source API, and MusicBrainz answers it with 400 Bad Request, logging a traceback once per affected file. _search_api now returns no candidates instead of issuing a request that cannot match anything.

To Do

• Documentation (bugfix, no user-facing option changed)
• Changelog.
• Tests. (test_search_api_skips_request_without_query_and_filters fails without the fix, passes with it.)

[Copilot]

Pull request overview

grug see PR fix metadata source search path. When query empty and filters empty, PR now skip API call so no more MusicBrainz 400 spam for junk files with no tags.

Changes:

• Add guard in SearchApiMetadataSourcePlugin._search_api to return no candidates when query+filters both empty.
• Add regression test to ensure empty search does not call provider and does not raise even when raise_on_error true.
• Add changelog entry for bug 🐛6862.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
beets/metadata_plugins.py	Skip doomed API request when both query and filters are empty; return empty result set.
test/test_metadata_plugins.py	Add regression test covering empty query+filters behavior.
docs/changelog.rst	Document the bugfix in the changelog.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.74%. Comparing base (dc1709e) to head (54b5d41).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6873   +/-   ##
=======================================
  Coverage   75.74%   75.74%           
=======================================
  Files         164      164           
  Lines       21437    21440    +3     
  Branches     3379     3380    +1     
=======================================
+ Hits        16237    16240    +3     
  Misses       4400     4400           
  Partials      800      800           

Files with missing lines	Coverage Δ
beets/metadata_plugins.py	85.02% <100.00%> (+0.27%)	⬆️

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[semohr]

Thanks! Please rebase onto master and fix the failing CI and we can merge this 👍

[Sanjays2402]

Rebased onto master (was 56 commits behind) and fixed the docs job. The only red check was Check docs, and the failure was docs/changelog.rst could be reformatted from poe format-docs --check — my entry's line wrapping didn't match docstrfmt after the reword. Reflowed it with docstrfmt 2.2.0, no wording change. Rebase was conflict-free and the diff against master is unchanged at 16 insertions across the three files. test/test_metadata_plugins.py is 16 passed locally.

[semohr]