There are several views that shows table items and an "add" button to add items to the table. However those modals forms don't check for duplicate names at the client side, so when the user submits a name that already exists, the server side will throw an error, on the client side a red panel shows an "unknown error" and the user should click at it to show the server response, often a "WFLYCTL0212: Duplicate resource".
To prevent this not intuitive behavior, I propose to create a form validator that checks for duplicate resources and warns the user in the form level, so the user will be able to fix the name before submit and prevent a waste of time.