Return 400 for invalid If-Match values

[aaronburtle]

Why make this change?

Closes #3397

What is this change?

When DeterminePatchPutSemantics threw a DataApiBuilderException for an invalid If-Match value, the exception was thrown before entering HandleOperation and the try-catch block within. This is where we convert DataApiBuilderException into structured JSON error response. We therefore move the DeterminePatchPutSemantics call inside of the try-catch block within HandleOperation, gating the function behind a check of the operation type so that it only applies to Upsert and UpsertIncremental operations.

How was this tested?

Added a test for Put and a test for Patch to validate the new behavior.

Sample Request(s)

Any valid Put or Patch with headers using If-Match with a value other than *

[Copilot]

Pull request overview

This PR fixes REST PUT/PATCH behavior so invalid If-Match header values correctly return a structured 400 Bad Request JSON error (instead of bubbling out and producing a 500/empty response), aligning REST error handling with DAB’s DataApiBuilderException conversion path.

Changes:

• Move DeterminePatchPutSemantics evaluation into HandleOperation’s try/catch so invalid If-Match values are translated into a 400 JSON error response.
• Gate DeterminePatchPutSemantics so it only applies to Upsert / UpsertIncremental.
• Add PUT and PATCH integration tests asserting 400 + expected error message for invalid If-Match values.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Service/Controllers/RestController.cs	Moves If-Match validation into the controller’s exception-handling path to return 400 JSON errors.
src/Service.Tests/SqlTests/RestApiTests/Put/PutApiTestBase.cs	Adds PUT test verifying invalid If-Match returns 400 with expected message.
src/Service.Tests/SqlTests/RestApiTests/Patch/PatchApiTestBase.cs	Adds PATCH test verifying invalid If-Match returns 400 with expected message.