[CH] core dump at toDecimalString with null value

### Backend

CH (ClickHouse)

### Bug description

sql:
```
create fact_table(
week_beg_dt date,
gmv decimal(19, 4),
total_items int
)
spark.sql(sql).show(10)

select sum(gmv), sum(total_items) from fact_table
where extract(month from week_beg_dt) = 13
```

exception:

### Spark version

None

### Spark configurations

_No response_

### System information

_No response_

### Relevant logs

_No response_