**Describe the bug**
```
SELECT number % 100 AS k, sumArray(emptyArrayUInt8()) AS v FROM numbers(10) GROUP BY k
```
Fails under ASan.

if (!data_variants.isTwoLevel())
            blocks.emplace_back(prepareBlockAndFillSingleLevel(data_variants, final));
        else
            blocks.splice(blocks.end(), prepareBlocksAndFillTwoLevel(data_variants, final, thread_pool.get()));
    }
    if (!final)
    {
        
        
        data_variants.aggregator = nullptr;
    }
    if (isCancelled())
        return BlocksList();
    size_t rows = 0;
    size_t bytes = 0;
    for (const auto & block : blocks)
    {
        rows += block.rows();
        bytes += block.bytes();
    }
    double elapsed_seconds = watch.elapsedSeconds();
    LOG_TRACE(log,
        "Converted aggregated data to blocks. {} rows, {} in {} sec. ({} rows/sec., {}/sec.)",
        rows, ReadableSize(bytes),
        elapsed_seconds, rows / elapsed_seconds,
        ReadableSize(bytes / elapsed_seconds));
    return blocks;
}
template <typename Method, typename Table>
void NO_INLINE Aggregator::mergeDataNullKey(