bug: sdk uninstall fails when local install target directory is missing

[chloe41427]

Summary

sdk uninstall fails when the installed version directory no longer exists (e.g. a local install pointing to a deleted or moved external path). This leaves SDKMAN! in a catch-22 state where the version cannot be uninstalled or reinstalled.

Originally reported in sdkman/sdkman-cli#407 (2016). The bug persists in the Rust implementation.

Steps to reproduce

1. Install a local version pointing to an external path:

   sdk install gradle myver /some/external/path
   

2. Delete or move the external path:

   rm -rf /some/external/path
   

3. Attempt to uninstall:

   sdk rm gradle myver
   

Actual behaviour

gradle myver is not installed on your system

But attempting to reinstall:

sdk install gradle myver /some/other/path

→ Stop! gradle myver is already installed.

The version entry (a broken symlink) still exists under ~/.sdkman/candidates/gradle/myver, but validate_version_path rejects it because the target directory is gone.

Expected behaviour

sdk uninstall should succeed when the version entry exists in the candidates directory, even if the underlying target has been deleted. It should clean up the broken symlink/directory entry and report success.

Root cause

validate_version_path in src/lib.rs (line 77) checks:

if version_path.exists() && version_path.is_dir()

Path::exists() returns false for broken symlinks. The function should also check for broken symlinks (e.g. version_path.symlink_metadata().is_ok()) or the uninstall command should handle the missing-target case separately.

Suggested fix

In the uninstall command, relax the validation: if the version directory entry exists as a symlink (even broken) or as a directory, proceed with removal. fs::remove_dir_all handles broken symlinks fine — the issue is purely in the pre-validation gate.