add: ws on error for unexpected http errors like 429

[OguzBey]

very critical fix

[OguzBey]

issue #171

[Copilot]

Pull Request Overview

This PR adds an error handler on the WebSocket client to surface unexpected HTTP errors (e.g., 429) via the existing #handleError method.

• Registers a new 'error' listener on this.#ws
• Invokes #handleError with a custom message and the error’s message property

Comments suppressed due to low confidence (1)

src/client.js:269

• There’s no test covering the WebSocket 'error' event handling. Consider adding a unit or integration test to verify that #handleError is invoked correctly when the WS emits an error.

this.#ws.on('error', (err) => {