Incorect message occurs after trying to safe already existed value in unique field

[MikhailSilk]

Environment

Custom front generator version: v. 4.0.0-beta.1

Description of the bug or enhancement

Create a new project Create a new entity Create a new attribute with unique validation Create a new entity management frontend component Run the project and open the created component for edition Create the first instance Try to save entity instance with an existing field

AR: Incorect message occurs.

[HegelPro]

For show a correct error message need to add details about wrong fields to server error.