fix: prevent decode error from being overwritten by Body.Close in decodeRequestBody

[cointem]

Problem:
In runtime.go, the function decodeRequestBody is declared with named return values.Inside it, the request body is closed using a defer that assigns to the named return variable err.This creates a bug because the deferred closure runs after the function has already decided what to return, but before the return values are actually returned to the caller. If JSON decoding fails, the function intends to return a non-nil error.However, when the deferred Close() runs, it overwrites the return variable err with the result of req.Body.Close().
fix:
The fix changes the defer to only propagate a Close() error if no earlier error is being returned:

If decoding (or any earlier step) already set err, we keep that error.
If err is still nil and Close() fails, we return the close error.
old code:

new code:

[gemini-code-assist]

Summary of Changes

Hello @cointem, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical bug in the decodeRequestBody function where a deferred call to close the request body could inadvertently overwrite a more significant JSON decoding error. The fix ensures that the original decoding error is preserved and returned, providing more accurate error reporting. A dedicated test case has been introduced to prevent future regressions of this specific issue.

Highlights

• Error Handling Logic: The decodeRequestBody function's defer statement has been updated to prevent a req.Body.Close() error from overwriting a pre-existing JSON decoding error. The Close() error is now only propagated if no other error has occurred earlier in the function.
• New Test Case: A new test file runtime_test.go has been added, including TestDecodeRequestBody_DoesNotOverwriteDecodeErrorOnClose, to specifically verify that decoding errors are correctly returned and not suppressed by subsequent Body.Close() operations.
• Copyright Year Update: The copyright year in server/adkrest/controllers/runtime.go has been updated from 2025 to 2026.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a bug where a JSON decoding error in decodeRequestBody could be overwritten by a nil error from the deferred req.Body.Close(). The change to conditionally assign the close error only when no other error has occurred is the right approach. The addition of a regression test is also excellent. I've added one suggestion to enhance the test coverage to also include the scenario where decoding succeeds but closing the body fails, which would make the test suite for this fix more robust.