Fix - WITH FILL would produce abort when FillingTransform processing empty block

[yakov-olkhovskiy]

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in official stable or prestable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Fix WITH FILL abort when FillingTransform processing empty block

Query example:

SELECT
    2 AS x,
    arrayJoin([NULL, NULL, NULL])
GROUP BY
    GROUPING SETS (
        (0),
        ([NULL, NULL, NULL]))
ORDER BY x ASC WITH FILL FROM 1 TO 10

result:

clickhouse: /home/ubuntu/ClickHouse-fill/src/Columns/ColumnVector.h:265: virtual DB::Field DB::ColumnVector<char8_t>::operator[](size_t) const
[T = char8_t]: Assertion `n < data.size()' failed.
Aborted (core dumped)

reported by fuzzer:
https://s3.amazonaws.com/clickhouse-test-reports/46731/5af6ac534e1ae4b6ea2384ed9b1cd723e9e22de8/fuzzer_astfuzzermsan/report.html

[alexey-milovidov]

Please also copy-paste the query to a new test.