**Describe the bug**
```
clickhouse-client --max_block_size 123 -n < 01130_in_memory_parts_nested.sql
```

Outputs an array with huge number of zeros that is definitely incorrect.
DataPartInMemoryPtr data_part_,
    NamesAndTypesList columns_,
    const StorageMetadataPtr & metadata_snapshot_,
    MarkRanges mark_ranges_,
    MergeTreeReaderSettings settings_)
    : IMergeTreeReader(data_part_, std::move(columns_), metadata_snapshot_,
        nullptr, nullptr, std::move(mark_ranges_),
        std::move(settings_), {})
    , part_in_memory(std::move(data_part_))
{
    for (const auto & name_and_type : columns)
    {
        auto [name, type] = getColumnFromPart(name_and_type);
        
        
        if (!part_in_memory->block.has(name) && typeid_cast<const DataTypeArray *>(type.get()))
            if (auto offset_position = findColumnForOffsets(name))
                positions_for_offsets[name] = *offset_position;
    }
}
size_t MergeTreeReaderInMemory::readRows(size_t from_mark, bool continue_reading, size_t max_rows_to_read, Columns & res_columns)