crate: Filtering on a column with `INDEX OFF` doesn't behave correctly

CrateDB version

5.4.0

Problem description

Filtering on a column with INDEX OFF doesn’t behave consistently.

Steps to Reproduce

cr> create table t(a int INDEX OFF);
CREATE OK, 1 row affected  (0.327 sec)

cr> select * from t where a = 1;
SQLParseException[Cannot search on field [a] since it is not indexed.]

this seems fine, but:

cr> select * from t where a > 1;
+---+
| a |
+---+
+---+
SELECT 0 rows in set (0.008 sec)

and:

cr> insert into t(a) values(2), (3);
INSERT OK, 2 rows affected  (0.043 sec)
cr> refresh table t;
REFRESH OK, 1 row affected  (0.003 sec)
cr> select * from t where a > 1;
+---+
| a |
+---+
+---+
SELECT 0 rows in set (0.003 sec)
cr> select * from t where a + 1 > 1;
+---+
| a |
+---+
| 3 |
| 2 |
+---+
SELECT 2 rows in set (0.008 sec)