discogs: don't crash if a release is deleted

[9999years]

Description

Detect an HTTPError when hitting the Discogs API to prevent a crash when a release has been deleted.

Before:

Traceback (most recent call last):
  File "/nix/store/yk2m7a9wdmh8fz8ywca0c73sc5ad2zm6-beets-2.3.1/lib/python3.13/site-packages/beetsplug/discogs.py", line 312, in get_album_info
    result.refresh()
    ~~~~~~~~~~~~~~^^
  File "/nix/store/007cfg4f295dz064bl9a2cjw10vlpc83-python3.13-discogs-client-2.8/lib/python3.13/site-packages/discogs_client/models.py", line 204, in refresh
    data = self.client._get(self.data['resource_url'])
  File "/nix/store/007cfg4f295dz064bl9a2cjw10vlpc83-python3.13-discogs-client-2.8/lib/python3.13/site-packages/discogs_client/client.py", line 114, in _get
    return self._request('GET', url)
           ~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/nix/store/007cfg4f295dz064bl9a2cjw10vlpc83-python3.13-discogs-client-2.8/lib/python3.13/site-packages/discogs_client/client.py", line 111, in _request
    raise HTTPError(body['message'], status_code)
discogs_client.exceptions.HTTPError: 404: That release does not exist or may have been deleted.

After:

Discogs release not found: <Release 20919814 'Kumi Tanioka, Yae - Final Fantasy Crystal Chronicles Original Soundtrack'>: 404: That release does not exist or may have been deleted.

Here's the link to the relevant release, which shows up in search results but 404s if you click on it: https://www.discogs.com/release/20919814-Kumi-Tanioka-Yae-Final-Fantasy-Crystal-Chronicles-Original-Soundtrack

To Do

• Documentation. (If you've added a new command-line flag, for example, find the appropriate page under docs/ to describe it.)
• Changelog. (Add an entry to docs/changelog.rst to the bottom of one of the lists near the top of the document.)
• Tests. (Very much encouraged but not strictly required.)

[github-actions]

Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.

[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 4 lines in your changes missing coverage. Please review.

Project coverage is 63.72%. Comparing base (0fec858) to head (189fbd1).

Files with missing lines	Patch %	Lines
beetsplug/discogs.py	55.55%	4 Missing ⚠️

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[github-actions]

Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.

[Copilot]

Pull Request Overview

This PR improves error handling in the Discogs plugin to prevent crashes when attempting to access deleted releases. The change gracefully handles HTTP 404 errors that occur when refreshing release data, logging a debug message instead of crashing the application.

• Adds HTTPError exception handling for deleted releases in the Discogs API
• Imports logging module and creates a global logger for error reporting
• Converts unhandled exceptions into debug log messages for better user experience