An optimistic row from useQuery().create() had no created_at (the server fills it), so for the moment the write was in flight, Intl.DateTimeFormat().format(new Date(row.created_at)) threw RangeError: Invalid time value and took the screen down.
The overlay row now carries a client stamp, replaced by the server's value on settle. Not sent to the server. Also fixes sort placement under the default -created_at.
Still true: an optimistic row lacks anything else the server fills (owner_id, column defaults) — pass what your UI reads into create(...).