fix(lsp): handle warmupClient initialization errors

[G-hoon]

Summary

Fix unhandled promise rejection in warmupClient() that causes process crash when LSP server fails to start.

Problem

warmupClient() uses a fire-and-forget pattern but had no error handling:

initPromise.then(() => {
  // success handling only
})
// ❌ No .catch() - unhandled rejection if start() or initialize() fails

When the LSP server binary is not found, has permission issues, or fails to initialize, the promise rejection goes unhandled, causing:

• UnhandledPromiseRejection error
• Process exit with code 1

Reproduction

lspManager.warmupClient("/tmp", {
  id: "fake-lsp",
  command: ["nonexistent-binary"],
  filetypes: ["fake"],
})
// Before: Exit code 1, UnhandledPromiseRejection
// After: Error logged, process continues normally

Solution

Add .catch() handler to:

1. Log the error with context (server ID)
2. Clean up the failed client from the map
3. Stop the client to release resources

Changes

• src/tools/lsp/client.ts: Add error handling to warmupClient() initialization promise

---

Summary by cubic

Handle LSP warmup initialization errors to prevent unhandled promise rejections and process crashes. warmupClient() now catches start/initialize failures, logs the error with server ID, removes the failed client, and stops it so the process keeps running.

^{Written for commit 161da10. Summary will update on new commits.}

[G-hoon]

I have read the CLA Document and I hereby sign the CLA

[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.