Server-side, return 200 with success: false and a friendly message when sendTestNotification reports failure (the underlying call already swallows the error); reserve real 500s for unexpected exceptions.
Client-side, teach usePost to honour the response body's success flag so success:false flips the toast to error without throwing through axios. Also tidy the toast container: drop icons, no wrapping, single-line ellipsis with a sensible max-width that hugs short messages.
Alex Holliday
harsh-aghara
gorkem-bwl