Native installer deletes working npm install but fails to create ~/.local/bin/claude launcher

Bug Description

Running curl -fsSL https://claude.ai/install.sh | bash on macOS reports "successfully installed" but:

1. Never creates ~/.local/bin/claude (the native launcher)
2. Never creates ~/.claude/local/ (the local npm install directory)
3. Deletes the existing working npm global install as a "cleanup" step

This leaves the user with a completely broken claude command.

Steps to Reproduce

1. Have Claude Code installed via npm: npm install -g @anthropic-ai/claude-code
2. Verify it works: claude --version → 2.1.42
3. Run the native installer: curl -fsSL https://claude.ai/install.sh | bash
4. Observe: output says "✔ Claude Code successfully installed!" with "Location: ~/.local/bin/claude"
5. Observe: warning says "installMethod is native, but claude command not found at /Users/rafael/.local/bin/claude"
6. Run claude --version → command not found
7. Check ls ~/.local/bin/claude → does not exist
8. Check ls ~/.claude/local/ → does not exist

What Happens Internally

From the debug log at ~/.claude/debug/:

Install: Starting installation process (force=false, target=undefined)
Install: Calling installLatest(channelOrVersion=stable, forceReinstall=false)
Checking for native installer update to version 2.1.32
Install: installLatest returned version=2.1.32, wasUpdated=true, lockFailed=false
Install: Setup launcher completed with 1 messages
Install: Setup message: installMethod is native, but claude command not found at /Users/rafael/.local/bin/claude
Install: Cleaning up npm installations after successful install
Removed global npm installation of @anthropic-ai/claude-code
Cleaned up 1 npm installation(s)

The flow is:

1. installLatest("stable") returns wasUpdated=true and version 2.1.32 — the install claims success
2. setupLauncher() fails to create ~/.local/bin/claude but returns a warning message instead of throwing an error
3. Because the install reported success, the cleanup function VdT() runs npm uninstall -g @anthropic-ai/claude-code, removing the user's working installation
4. The bootstrap script's cleanup then removes the downloaded binary with rm -f "$binary_path"

Net result: old install deleted, new install never materialized.

Expected Behavior

• If the launcher at ~/.local/bin/claude is not created, the install should fail (not report success)
• The cleanup step should not remove existing working installations if the native install didn't succeed
• At minimum, the cleanup should verify ~/.local/bin/claude exists and is executable before removing the npm global install

Environment

• macOS 26.2 (Tahoe / Darwin 25.2.0)
• Apple Silicon (arm64)
• Node.js v22.14.0 (via nvm)
• Claude Code 2.1.42 (was installed via npm install -g @anthropic-ai/claude-code)
• Shell: zsh

Workaround

Reinstall via npm:

npm install -g @anthropic-ai/claude-code