[ENHANCEMENT] Improved Input Validation and Error Handling

[AshubShafqat]

Closes #140

🚀 Summary

This PR improves system robustness by enhancing input validation and error handling across the application.

✅ Changes Made

• Refactored app.py for cleaner structure and added global error handling
• Added validation for LLM name and keywords in routes
• Implemented try-catch blocks to prevent runtime crashes
• Improved error responses with proper status codes
• Removed unnecessary temporary file

🧪 Testing

• Tested routes with valid and invalid inputs
• Verified behavior for missing parameters
• Ensured no breaking changes in existing functionality

📌 Impact

• Improves reliability and stability
• Prevents crashes due to invalid inputs
• Aligns with best practices for Flask applications

[AshubShafqat]

This PR focuses on improving validation and error handling without affecting existing workflows. Open to feedback and improvements.

[AshubShafqat]

Hi @hardik1408 @nipuna — I've updated this PR to address issue #140
(Lack of input sanitisation on keywords endpoint).

Latest changes now include:

• ✅ Linked to issue Lack of input sanitisation on keywords endpoint #140 (Closes Lack of input sanitisation on keywords endpoint #140)
• ✅ Added unit tests in tests/test_input_validation.py covering:
  • Empty/missing keyword → 400 response
  • Script injection rejected
  • SQL injection rejected
  • Invalid LLM name handling
  • Global 404 returns JSON not HTML

Would really appreciate a review! Happy to make any adjustments.
Also planning to work on the email subscription feature next.

[AshubShafqat]

Note to maintainers: Parts of this PR were developed with
AI assistance (Assisted-By: Claude/AI) as per the
contributing guidelines.