fix: nil error SEGFAULT

[zfields]

• Performs nil check on error before dereference
• Lowercases request type value in schema file path
• Provides launch.json for debugging notecard and notehub CLIs
• Improves error message readability for unknown request.

[Copilot]

Pull Request Overview

This PR addresses a SEGFAULT issue by adding a nil check before an error is dereferenced, improves error message clarity for unknown requests, and adds a launch.json file for CLI debugging.

• Adds a nil check in formatErrorMessage to prevent a nil-pointer dereference.
• Updates resolveSchemaError to improve error message readability and to handle unknown request types by checking file existence.

Files not reviewed (1)

• .vscode/launch.json: Language not supported

[Bucknalla]

LGTM