Fix: 404 Error Handler Crash

[nikhil1205-ai]

Description

This PR fixes the crash in the error handling system by removing the dependency on g.news_controller and introduces a generic error handler that captures all exceptions and renders a user-friendly HTML error page.

Related Issue

Fixes: #170

Motivation and Context

Previously, the 404 error handler relied on g.news_controller, which may not be initialized when a request hits an invalid route. This caused runtime errors and application crashes.

Additionally, error handling was limited and inconsistent across different types of failures.

This change introduces a centralized error handling mechanism that:

• Handles all exceptions (404, 500, etc.)
• Avoids reliance on request-scoped objects like g
• Improves user experience by rendering a clean error page

How Has This Been Tested?

Ran the Flask application locally:

flask --app app.py run

Tested invalid route:

http://127.0.0.1:5000/invalid-route
Verified:
No crash occurs

• Error page (error.html) is rendered
• Correct status code is returned (e.g., 404)

Tested runtime error scenarios:

• Simulated internal errors
• Confirmed 500 error page is displayed

Environment:

• OS: Windows 10
• Browser: Chrome (latest version)

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.