Andreas Svanberg a0fd84343c Show error message when trying to add duplicate exemptions ()
Fixes 

## How to test
1. Log in as admin
2. Go to "Admin / Match / Application periods"
3. Click "Edit exemptions" on the period
4. Add the same exemption twice to "Sture Student"

Reviewed-on: 
Reviewed-by: Nico Athanassiadis <nico@dsv.su.se>
Co-authored-by: Andreas Svanberg <andreass@dsv.su.se>
Co-committed-by: Andreas Svanberg <andreass@dsv.su.se>
2025-02-20 13:56:13 +01:00
..