🐛 Bug Report: `Tracker.tsx` — `authError` always `undefined` because `useGitHubAuth` does not expose an `error` field

[ananyadarna]

📜 Description

In src/pages/Tracker/Tracker.tsx, authError is destructured from
useGitHubAuth() using error: authError. However, useGitHubAuth
never returns an error field, so authError is always undefined.
This means auth-related errors are silently swallowed and never shown
to the user.

Expected behavior

Auth-related errors should be surfaced to the user via the Alert component.

Steps to reproduce

1. Open /track in the app
2. Trigger an auth-level error (e.g. invalid token)
3. No error message appears in the UI despite the failure

What browsers are you seeing the problem on?

No response

📃 Relevant Screenshots (Links)

No response