problems sorting QAbstractItemModel without QSortFilterProxyModel

[TheRonin]

I have a custom QAbstractItemModel connected to a QTreeView. The model supports a basic two-tiered item hierarchy with nodes and sub-nodes. The code that i have attempts to sort the sub-nodes based on an internal attribute whenever they are added or updated.

for example:

Node* TreeModel::addSubNode(Node* parent)
{
  Node* subnode = new Node(Node::SubNode, parent->getId());
 
  QModelIndex parentIndex = getIndexForNode(parent);
  int position = parent->getChildCount();
 
  beginInsertRows(parentIndex, position, position);
  parent->addChild(subnode);
  endInsertRows();
 
  emit layoutAboutToBeChanged();
  parent->sortSubNodes();
  emit layoutChanged();
 
  return subnode;
}
 
bool lessThan(Node* node1, Node* node2)
{
  return node1->getValue() < node2->getValue();
}
 
void Node::sortSubNodes()
{
  qSort(children.begin(), children.end(), lessThan);
}

Node* TreeModel::addSubNode(Node* parent)
{
  Node* subnode = new Node(Node::SubNode, parent->getId());

  QModelIndex parentIndex = getIndexForNode(parent);
  int position = parent->getChildCount();

  beginInsertRows(parentIndex, position, position);
  parent->addChild(subnode);
  endInsertRows();

  emit layoutAboutToBeChanged();
  parent->sortSubNodes();
  emit layoutChanged();

  return subnode;
}

bool lessThan(Node* node1, Node* node2)
{
  return node1->getValue() < node2->getValue();
}

void Node::sortSubNodes()
{
  qSort(children.begin(), children.end(), lessThan);
}

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Adding nodes and sub-nodes works fine, but when i start to remove them things start breaking down. A segfault tends to appear in beginRemoveRows with a QModelIndex with an invalid internalPointer. I'm fairly confident however that i only create nodes with pointers to valid parents. If i don't do the sorting the crash dissapears and things seem stable. Is it possible to do the sorting in this way or must i add a QSortFilterProxyModel?

Thank you for your time,
/TR