sql: investigate why no error occurs

On 02065f5bf9ff49bcd5b8e01577933c5bb0de0ef4 the following logic test should result in an error but I get no error:
```
# LogicTest: local

statement ok
CREATE TABLE t108901 AS SELECT g::FLOAT8 AS _float8 FROM generate_series(1, 5) AS g;

statement error integer out of range
SELECT 1 FROM t108901 WHERE
EXISTS(
SELECT regr_slope(1.2345678901234562e+27::FLOAT8::INT8,0.968018273253753::FLOAT8::DECIMAL) OVER ()::FLOAT8
FROM t108901
);
```

Jira issue: CRDB-30722