lvm-dbus: Show better error for invalid LVM IDs

[vojtechtrefny]

LVM DBus uses assert to check for empty IDs so it produces error which isn't easy to decipher.

[gemini-code-assist]

Summary of Changes

Hello @vojtechtrefny, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the LVM DBus interface by making error reporting more explicit and user-friendly. It addresses a scenario where providing an invalid or empty LVM ID would previously result in an obscure assertion failure. The change introduces a direct check for such invalid IDs, ensuring that callers receive a clear and actionable error message, thereby improving the robustness and debuggability of applications interacting with the LVM DBus service.

Highlights

• Error Handling: Improved error handling in the get_lvm_object_properties function by explicitly checking for NULL or empty LVM IDs. Instead of relying on an assert that would lead to a cryptic error, a specific BD_LVM_ERROR_NOEXIST is now returned with a clear message: "Invalid LVM ID specified".

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[gemini-code-assist]

Code Review

This pull request aims to provide a better error message for invalid LVM IDs by adding a check for NULL or empty obj_id in get_lvm_object_properties. The change is a good step, but I've identified a critical issue and an opportunity for refactoring. The current implementation in get_lvm_object_properties has a bug that can lead to a crash and also duplicates code from another function, get_object_path. My review includes a suggestion to refactor the function to fix the bug and improve code quality. I also noted that get_object_path has the same vulnerability and should be fixed for a complete solution.