Urgent React eCommerce Bug Fixing

I have a small eCommerce demo application that requires debugging and fixing. You will receive access to a small project containing both frontend and backend code. The application is currently partially broken and needs to be fixed so that all core features function correctly. Your job is to identify and fix issues in the system while keeping the existing structure intact.

Here’s what needs to be fixed:

• Cart total calculation is incorrect (price formatting/type issues)
• Backend API route(s) are misconfigured or returning errors
• Frontend useEffect / state management bug causing duplicate or incorrect data rendering

Expected Deliverables:
• Correct cart total calculation
• Working backend API endpoints
• Clean, error-free console output

Since this is a simple and urgent project, I want to finish this project within four hours.