Enhance database operations for better debugging

[deldesir]

🚀 Pull Request Overview:

This pull request includes the following enhancements to the download task:

• Improved error handling for download failures with detailed error messages.
• Enhanced database operations to handle errors and provide clearer messages.
• Improved retrieval of requested files and shelf title from the SQLite database.

These changes aim to make the download process more robust and provide users with better information about download failures.

📋 Checklist:

• Tested the changes thoroughly.
• Checked for backward compatibility (bookshelf feature)

🔗 Related Issues:
Issue #89

📌 Testing scenarios:
See Issue #97

cc @EMG70

[holta]

1. @deldesir how does this quick test of PR Enhance database operations for better debugging #96 look to you?

   iiab-diagnostics: https://sprunge.us/16LYXQ?en#n-873

2. What aspects of PR Enhance database operations for better debugging #96 should @EMG70 test most urgently on Tuesday (i.e. in coming hours, if he happens to have time!!)

3. ASIDE: Are /var/log/calibre-web.log blank lines on 962 and 1001 something we should clean up? (Or is that an upstream Calibre-Web issue we should not get involved with for now?)

[deldesir]

1. @deldesir how does this quick test of PR Enhance database operations for better debugging #96 look to you?
   iiab-diagnostics: https://sprunge.us/16LYXQ?en#n-873

Looks clean to me. With this info, we know which commits/PR is being tested

2. What aspects of PR Enhance database operations for better debugging #96 should @EMG70 test most urgently on Tuesday (i.e. in coming hours, if he happens to have time!!)

Backward compatibility, ensuring playlists download without an itch.

3. ASIDE: Are /var/log/calibre-web.log blank lines on 962 and 1001 something we should clean up? (Or is that an upstream Calibre-Web issue we should not get involved with for now?)

Not very important, but we'll keep an eye to it so someday we can look into it.

[holta]

3. What aspects of PR Enhance database operations for better debugging #96 should @EMG70 test most urgently on Tuesday (i.e. in coming hours, if he happens to have time!!)

Backward compatibility, ensuring playlists download without an itch.

@deldesir Are you saying this PR #96 solves... ?

• Playlist downloads will report a 500 INTERNAL SERVER ERROR #98

(Thanks for clarifying & explaining so there's no ambiguity!)

[deldesir]

Yes, but not without #99

[holta]

Yes, but not without #99

Motivations behind PR #99 are not (yet!) clear to me and @EMG70:

If it's blocking testing or other PR's (not great, but Ok!) then please prioritize helping everyone in understanding PR #99's motivations, Thank You! 💯

[holta]

PR #99 appears to contain serious problems based on a misunderstanding as to where we are headed:

So hopefully merging this PR #96 can serve as a basis for reworking PR #99 — moving us all (baby steps! one step at a time!) — towards what's actually needs... 🙏