typeOverrides object that specifies all the schemas that should be applied to createInsertSchema and createSelectSchema. Depending on the schema, the override would be applied and then the nullability of the column would be applied on top of the refinement.preferences is a nullable json field. The way this example overwrites the nullability, you can easily insert null values into the preferences field but using the userSelectSchema to parse data coming out of the DB would fail.jsonb fields. It made a lot of sense when I could refine the schema, and then have the nullability applied on top of the refinement.