/clear errors with 'Path does not exist' when referenced worktree directory was removed

Summary

Running /clear in a session fails with:

Error: Path "/Users/kyleroot/Code/eNobleon/data-forge/.claude/worktrees/350-emit-per-stage-completion-events" does not exist

The referenced worktree directory has since been cleaned up (the parent .claude/worktrees/ is empty), but /clear still tries to resolve it and bails out instead of recovering gracefully.

Steps to reproduce

1. Start a session inside a Claude Code-managed worktree under .claude/worktrees/<slug>/.
2. Remove that worktree directory (e.g. after the work merges and the worktree is cleaned up).
3. From any session that still references the removed path, run /clear.
4. /clear errors instead of clearing.

Expected

/clear should either:

• detect the missing path and clear anyway, or
• detect the missing path and emit a recoverable warning while still clearing session state.

Actual

/clear aborts with a hard error and the session can't be cleared.

Environment

• Claude Code: 2.1.153
• macOS (Darwin 25.5.0)
• Shell: zsh
• Repo state at time of error:
• cwd: /Users/kyleroot/Code/eNobleon/data-forge
• .claude/worktrees/ exists but is empty
• git worktree list shows only the main checkout

Notes

This looks like stale state being persisted somewhere (possibly the session/transcript file) pointing at a worktree path that has since been removed. A defensive existence check before the path is consumed by /clear would fix it.