Improve error handling during package installation

[realfakenerd]

Description

This PR enhances the install_package_if_needed logic in src/svelte.rs to make the LSP installation process more robust and resilient to network or permission failures.

Previously, the installation logic was overly optimistic, potentially failing silently and leading to downstream crashes when trying to spawn the language server from a non-existent or corrupted directory.

Changes

• Explicit Error Reporting: Replaced the silent failure approach with an explicit match statement on zed::npm_install_package. If the installation fails and no cached version is available, it now returns a descriptive critical error.
• Integrity/Sanity Check: Added a post-installation check using fs::metadata to verify that the package_path directory actually exists on disk before marking the package as successfully installed.

[ghostdevv]

hey, thanks for the PR! I'm curious what the motivation is? did this solve/help debug a tangible issue for you?

[realfakenerd]

Hey man @ghostdevv! sorry for the delay, lot of things happening at the same time in my life. Well it was more of a preventive measure, while looking at the installation logic i noticed it was a bit optimistic and could fail silently. I wanted to make the process more robust. I am still learning rust and collaborating on github, so if i made something wrong, tell me :)