Overview of the Feature Request
In trying to debug a use of the Semantic API, I realized that the detailed error created in the class handling the call (in this case: Can't append to a single-value field that already has a value: https://dataverse.org/schema/core#dataAccessPlace) was being replaced by a generic Bad Request. The API request cannot be completed with the parameters supplied. Please check your code for typos, or consult our API guide at http://guides.dataverse.org. in our WebApplicationExceptionHandler class.

What existing behavior do you want changed?
Incorporate the problem-specific error message in the response to the user.

Are you thinking about creating a pull request for this feature?
Yes