I have approved. The only comment that I have is that the mapStructure method should focus purely on data transformation (mapping input to struct) and return errors, while HTTP response handling should be completely separate. But this was already there before this PR.

There is no need for this status to be checked for each endpoint where we are calling the mapStructure. In future this can grow and lead to unexpected responses and it definitely complicates the logic of the mapStructure.

from the practical perspective, I somewhat agree with the response handling as it is now because otherwise the error responses should be handled the same way on each endpoint which is redundant. Nevertheless, you are also right about these specific errors are not necessary to be checked in every case. From my side, I would go with this as it is a fix PR and did not intend to break the original structure.