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

else if (result.type != AggregatedDataVariants::Type::without_key)
            throw Exception("Unknown aggregated data variant.", ErrorCodes::UNKNOWN_AGGREGATED_DATA_VARIANT);
    }
    if (isCancelled())
        return {};
    Block block;
    if (result.type == AggregatedDataVariants::Type::without_key || is_overflows)
        block = prepareBlockAndFillWithoutKey(result, final, is_overflows);
    else
        block = prepareBlockAndFillSingleLevel(result, final);
    
    if (!final)
    {
        
        result.aggregator = nullptr;
    }
    size_t rows = block.rows();
    size_t bytes = block.bytes();
    double elapsed_seconds = watch.elapsedSeconds();
    LOG_TRACE(log, "Merged partially aggregated blocks. {} rows, {}. in {} sec. ({} rows/sec., {}/sec.)",
        rows, ReadableSize(bytes),
        elapsed_seconds, rows / elapsed_seconds,
        ReadableSize(bytes / elapsed_seconds));
    if (isCancelled())
        return {};
    block.info.bucket_num = bucket_num;
    return block;
}
template <typename Method>
void NO_INLINE Aggregator::convertBlockToTwoLevelImpl(