Inconsistent `null value not allowed for object key` error from `jsonb_object_agg` function

**Describe the problem**

Inconsistent `null value not allowed for object key` error from `jsonb_object_agg` function

**To Reproduce**

The following code errors on the second select statement, but not the first:

```sql
CREATE TABLE foo (
tags JSONB NOT NULL
);
INSERT INTO foo VALUES ('{}');

SELECT jsonb_object_agg(key, value)
FROM jsonb_each('{}'::JSONB)
WHERE FALSE;

SELECT (
SELECT jsonb_object_agg(key, value)
FROM jsonb_each(tags)
WHERE FALSE
)
FROM foo;
```

**Expected behavior**

I don't see any functional difference between the two statements so I expect both to work

**Additional data / screenshots**

Both select statements succeed in postgres: https://onecompiler.com/postgresql/42tjfgu8r

**Environment:**
- CockroachDB version 24.2.3
- Server OS: CockroachDB Cloud
- Client app: psql

Jira issue: CRDB-42607