Uninformative error message on aspect unique business key constraint violation

[tushkanova]

When trying to create aspect with not unique business key user now receives message "Aspect with such name already exists (Aspect 1)" which is uninformative. Error message in this case should be smth like "Aspect business key is not unique. Aspect with such name and subject already exists (Aspect 1, Subject 1)"

[sreznick]

More detailed error reprting and backend side is needed + propagation of error message on fronend side