Refactor exception handling in GlobalExceptionHandler and improve error

[ma-mirzaei]

This pull request refactors and improves error handling in the VSUM project setup service, making error responses more consistent, user-friendly, and testable. The main changes include switching to a custom JSON error response for all exceptions, enhancing error messages for input validation, and adding dedicated tests for error handling.

Error handling and response improvements:

• Refactored GlobalExceptionHandler to write all error responses directly as JSON to the HTTP response (instead of returning ResponseEntity), ensuring consistent error format for all endpoints. Introduced a reusable writeErrorResponse method and switched to using HttpServletRequest/HttpServletResponse in exception handlers. [1] [2]

• Updated error messages in VsumProjectBuildService to be more descriptive, including the actual counts of uploaded files when metamodel and genmodel file counts do not match.

Testing improvements:

• Added a new test class VsumControllerErrorHandlingTest to verify that the API returns a proper JSON error response (with correct status and message) when a client requests a ZIP but an input validation error occurs.

• Updated existing tests in VsumProjectBuildServiceTest to assert the improved error messages, ensuring they contain both the descriptive message and the file counts. [1] [2]

Error context improvements:

• Enhanced exception messages in VsumProjectBuildService to include the underlying exception message or reason for both IO and interruption errors, providing more context in error responses.…or messages in VsumProjectBuildService