https://clickhouse-test-reports.s3.yandex.net/19868/c39ee3f58c85de0f2a7b609377e2f138305dc745/fuzzer_debug/report.html#fail1
{
    Block current_block_with_sharding_key_expr = source_block;
    storage.getShardingKeyExpr()->execute(current_block_with_sharding_key_expr);
    const auto & key_column = current_block_with_sharding_key_expr.getByName(storage.getShardingKeyColumnName());
    return storage.createSelector(cluster, key_column);
}
Blocks DistributedBlockOutputStream::splitBlock(const Block & block)
{
    auto selector = createSelector(block);
    
    const size_t num_shards = cluster->getShardsInfo().size();
    Blocks splitted_blocks(num_shards);
    for (size_t shard_idx = 0; shard_idx < num_shards; ++shard_idx)
        splitted_blocks[shard_idx] = block.cloneEmpty();
    size_t columns_in_block = block.columns();
    for (size_t col_idx_in_block = 0; col_idx_in_block < columns_in_block; ++col_idx_in_block)
    {
        MutableColumns splitted_columns = block.getByPosition(col_idx_in_block).column->scatter(num_shards, selector);
        for (size_t shard_idx = 0; shard_idx < num_shards; ++shard_idx)
            splitted_blocks[shard_idx].getByPosition(col_idx_in_block).column = std::move(splitted_columns[shard_idx]);
    }
    return splitted_blocks;
}
void DistributedBlockOutputStream::writeSplitAsync(const Block & block)