Custom`Delegate::destroyEditor()` is not called for some editor when removing a tree branch

class TreeModel
    : public QAbstractItemModel
{
public:
    struct MNode
    {
        MNode * parent;
        int self_row_num;
        std::vector<std::unique_ptr<MNode>> children;
    public:
        MNode(MNode * parent, int self_row_num)
            : parent(parent)
            , self_row_num(self_row_num)
            , children()
        {}
    };
private:
    std::unique_ptr<MNode> root_mnode;
public:
    TreeModel()
    {
        root_mnode = std::make_unique<MNode>(nullptr, 0);
        //auto & l1_node = root_mnode->children.emplace_back(std::make_unique<MNode>(root_mnode.get(), 0));
        //auto & l2_node = l1_node->children.emplace_back(std::make_unique<MNode>(l1_node.get(), 0));
    }
public:
    static MNode * retrieveMNodeFromIndex(QModelIndex const & index)
    {
        auto r = static_cast<MNode *>(index.internalPointer());
        return r;
    }
public:
    virtual QModelIndex index(int row, int column, QModelIndex const & parent = QModelIndex()) const override
    {
        if (row < 0 || column < 0)
            return QModelIndex();
        if (column >= 1)
            return QModelIndex();
        if (false == parent.isValid())
        {
            if (row != 0)
                return QModelIndex();
            return createIndex(0, column, static_cast<void *>(root_mnode.get()));
        }
        assert(parent.column() == 0);//Only the first column can be parent.
        auto parent_mnode = retrieveMNodeFromIndex(parent);
        assert(parent_mnode);
        if (row >= parent_mnode->children.size())
            return QModelIndex();
        return createIndex(row, column, static_cast<void *>(parent_mnode->children[row].get()));
    }
    virtual QModelIndex parent(QModelIndex const & index) const override
    {
        if (false == index.isValid())
            return QModelIndex();
        auto mnode = retrieveMNodeFromIndex(index);
        assert(mnode);
        auto parent_mnode = mnode->parent;
        if (!parent_mnode)
            return QModelIndex();
        return createIndex(parent_mnode->self_row_num, 0, static_cast<void *>(parent_mnode));
    }
    virtual int rowCount(QModelIndex const & parent = QModelIndex()) const override
    {
        if (false == parent.isValid())
            return 1;
        if (parent.row() < 0)
            return 0;
        if (parent.column() != 0)
            return 0;
        auto parent_mnode = retrieveMNodeFromIndex(parent);
        assert(parent_mnode);
        return parent_mnode->children.size();
    }
    virtual int columnCount(QModelIndex const & parent = QModelIndex()) const override
    {
        if (false == parent.isValid())
            return 1;
        if (parent.row() < 0)
            return 0;
        if (parent.column() != 0)
            return 0;
        return 1;
    }
    virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override
    {
        if (orientation == Qt::Vertical)
            return QAbstractItemModel::headerData(section, orientation, role);
        if (role != Qt::DisplayRole)
            return QAbstractItemModel::headerData(section, orientation, role);
        if (section == 0)
            return "Data";
        else
            return {};
    }
    virtual QVariant data(QModelIndex const & index, int role = Qt::DisplayRole) const override
    {
        if (false == index.isValid())
            return {};
        if (role != Qt::DisplayRole)
            return {};
        auto mnode = retrieveMNodeFromIndex(index);
        assert(mnode);
        if (index.column() == 0)
            return mnode->self_row_num;
        return {};
    }
public:
    virtual bool insertRows(int row, int count, const QModelIndex & parent = QModelIndex()) override
    {
        if (false == parent.isValid())
            return false;
        if (row < 0)
            return false;
        if (count != 1)
            return false;
        auto parent_mnode = retrieveMNodeFromIndex(parent);
        assert(parent_mnode);
        if (row != parent_mnode->children.size())
            return false;
        beginInsertRows(parent, row, row);
        parent_mnode->children.emplace_back(std::make_unique<MNode>(parent_mnode, row));
        endInsertRows();
        return true;
    }
    virtual bool removeRows(int row, int count, const QModelIndex & parent = QModelIndex()) override
    {
        if (false == parent.isValid())
            return false;
        if (row < 0)
            return false;
        if (count != 1)
            return false;
        auto parent_mnode = retrieveMNodeFromIndex(parent);
        assert(parent_mnode);
        if (row + 1 != parent_mnode->children.size())
            return false;
        beginRemoveRows(parent, row, row);
        parent_mnode->children.pop_back();
        endRemoveRows();
        return true;
    }
};

class MyLabel : public QLabel
{
    std::vector<char> v;
public:
    MyLabel(QWidget * parent = nullptr)
        : QLabel(parent)
    {
        v.resize(100 * 1024 * 1024);
    }
    ~MyLabel()
    {
        __nop();//for debug break point
    }
};
class Delegate
    : public QItemDelegate
{
public:
    virtual QWidget * createEditor(QWidget * parent, QStyleOptionViewItem const & /*option*/, QModelIndex const & index) const override
    {
        __nop();//for debug break point
        auto mnode = TreeModel::retrieveMNodeFromIndex(index);
        auto r = new MyLabel(parent);
        r->setText(QString::number(mnode->self_row_num));
        r->setAutoFillBackground(true);
        r->setFrameShape(QFrame::StyledPanel);
        r->setFrameShadow(QFrame::Sunken);
        return r;
    }
    virtual void destroyEditor(QWidget * editor, QModelIndex const & index) const override
    {
        __nop();//for debug break point
        return QItemDelegate::destroyEditor(editor, index);
    }
};

int main(int argc, char ** argv)
{
    QApplication app{ argc, argv };
    int r = 0;

    TreeModel model;
    Delegate delegate;
    QTreeView view;
    view.setModel(&model);
    view.setItemDelegateForColumn(0, &delegate);
    auto index0 = model.index(0, 0, QModelIndex());
    view.openPersistentEditor(index0);
    view.show();

    QPushButton button;
    button.setText("Push Me");
    QObject::connect(&button, &QPushButton::clicked, [&]()
        {
            model.insertRow(0, index0);
            auto index1 = model.index(0, 0, index0);
            view.openPersistentEditor(index1);
            model.insertRow(0, index1);
            auto index2 = model.index(0, 0, index1);
            view.openPersistentEditor(index2);
            model.removeRow(0, index0);
        });
    button.show();

    r = app.exec();
    return r;
}