JSON doesn't have undefined, only null the partial updates approach works ok for updating 'schemaful' data, where it could only ever mean to set the field to n

JSON doesn't have undefined, only null the partial updates approach works ok for updating 'schemaful' data, where it could only ever mean to set the field to null and could never delete the field from the object altogether but for editing a JSON document or other schemaless data then both operations are possible and you'd need to be able to distinguish them