[BUG]: Fix potential crashes and improve state handling in Output component

[Adilkhan6465]

Bug Description

📌 Problem

The Output component had multiple issues related to stability, state handling, and React best practices, which could lead to crashes or inconsistent behavior.

⚠️ Issues Identified

1. Potential Crash (High Priority)

• Accessing qaPairsFromStorage["output"] without checking existence could cause runtime crashes

2. Incorrect Default State

• questionType could be null if not found in localStorage, leading to unexpected behavior

3. Memory Leak Risk

• Web Worker was not safely cleaned up in all scenarios

4. Direct DOM Manipulation

• Dropdown was handled using direct DOM methods instead of React state

5. Unsafe localStorage Parsing

• Default structure from localStorage could lead to type mismatch issues

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✅ Fix Implemented

• Added safety checks before accessing qaPairsFromStorage["output"]
• Provided fallback value for questionType
• Ensured proper cleanup of Web Worker
• Refactored dropdown logic using useState and useRef
• Improved handling of parsed localStorage data

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💡 Benefits

• Prevents runtime crashes
• Improves application stability
• Aligns with React best practices
• Safer and more predictable state handling
• Cleaner and more maintainable code

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📍 Affected File

• eduaid_web/src/pages/Output.jsx

Steps to Reproduce

No response

Logs and Screenshots

No response

Environment Details

No response

Impact

Critical - Application is unusable

Code of Conduct

• I have joined the Discord server and will post updates there
• I have searched existing issues to avoid duplicates