fix: preserve exception context and return structured error responses

[arnchlmcodes]

Fix: Preserve exception context and return consistent API error responses

This PR fixes incorrect exception re-raising in several routes where raise IOError / raise OSError was used inside except blocks.

Using raise IOError creates a new empty exception, which discards the original error message and traceback. As a result, when failures occur the API returns a generic 500 error with little or no debugging information.

---

Problem

The previous pattern:

except IOError:
    raise IOError

replaces the original exception instead of propagating it. This removes important context such as the file path, system error message, and traceback, making debugging difficult and producing unclear API responses.

---

Changes

• Replaced incorrect exception re-raises with structured error handling:

except IOError as e:
    return jsonify({
        "error": str(e),
        "type": type(e).__name__
    }), 500

• Applied consistently across affected locations in:
  • CaseRoute.py
  • UploadRoute.py

---

Result

• Original exception details are preserved
• API responses now contain meaningful error information
• Debugging server-side failures becomes significantly easier
• Prevents silent loss of exception context

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[arnchlmcodes]

Closed as #33 adrdesses this