fix: improve websocket and watcher cleanup handling

[productdevbook]

Summary

• Add null checks before closing websocket and listener to prevent errors
• Use listener.close() instead of listener.server.close() for proper cleanup
• Remove all listeners from watcher before closing to prevent memory leaks

Changes

• Added conditional checks for websocket and listener existence before closing
• Fixed listener close method call
• Added removeAllListeners() call for watcher cleanup
• Added null check for watcher in close hook

Test plan

• Verify that the development server starts normally
• Confirm that websocket connections work as expected
• Test that the server closes cleanly without errors when stopping
• Ensure no memory leaks occur during server restarts

[vercel]

@productdevbook is attempting to deploy a commit to the NuxtLabs Team on Vercel.

A member of the Team first needs to authorize it.

[pkg-pr-new]

npm i https://pkg.pr.new/@nuxt/content@3478

commit: c08fbde

[farnabaz]

I guess you missed db.close()

[productdevbook]

yes, thank you.