In the Categories table, leaving an empty category name (and leaving focus) shows an error popup in the bottom-left corner: "Invalid value for property 'name'. Expected 'string', received 'null'"

While this is clear for a programmer, this should be gracefully handled with either a proper localized and readable string for common users, or better, no error message at all and a clever visualization of invalid field directly in UI (such as field being surrounded in red or being replaced with some valid default text if user exits field focus leaving it empty.