protected function getLastRow(BlockInterface $block)
    {
        if ($block->hasAttribute('last_row')) {
            $row = $block->get($block->getAttribute('last_row'));

            // return current row
            if (\count($row) < $row->getOption('column')) {
                return $row;
            }
        }

        // new row
        $rowName = BlockUtil::createUniqueName();
        $block->add($rowName, PanelRowType::class);

        return $block->get($rowName);
    }