Null constraint not throws

```sql
create table t (id int not null);
```

```clojure
(<!! (db/execute db ["insert into t (id) values ($1);" 9]))  ;; => {:updated 1 :rows []}
(<!! (db/execute db ["insert into t (id) values ($1);" nil])) ;; => {:updated 0 :rows []} instead of an error
```

platform:
PostgreSQL 11 + Java 8 + clojure 1.10