Add specific feedback for errors
If a member is already in a group (eg Kulturteam) and I want to add this specific person, the only feedback is "There's an error in an object". It would be nice to have different feedbacks for different problems. (Person is already in the group, person is not a VSETH member etc) In principle it would be nice to add these specific feedbacks in every way possible. For example if a cell is empty while adding a new event it would be better to see whats the problem instead of just getting "There's an error in an object".