collection: Fix potential invalid memory access

Refs #69290

src/collectioninterface.hpp

@@ -22,6 +22,7 @@ template<typename T> class ItemBase;
 
 class CollectionInterfacePrivate {
 public:
+   CollectionInterfacePrivate() : m_pParent(nullptr){}
 
    ///The backend parent of nullptr
    CollectionInterface*          m_pParent    ;

src/collectionmodel.cpp

@@ -220,7 +220,7 @@ QModelIndex CollectionModel::parent( const QModelIndex& idx ) const
 
 QModelIndex CollectionModel::index( int row, int column, const QModelIndex& parent ) const
 {
-   if (parent.isValid()) {
+   if (parent.isValid() && parent.model() == this && row < rowCount(parent)) {
       CollectionModelPrivate::ProxyItem* parentItem = static_cast<CollectionModelPrivate::ProxyItem*>(parent.internalPointer());
       CollectionModelPrivate::ProxyItem* item = nullptr;
       if (row < parentItem->m_Children.size())

src/fallbackpersoncollection.cpp

@@ -173,7 +173,7 @@ QString FallbackPersonCollection::name () const
 
 QString FallbackPersonCollection::category () const
 {
-   return QObject::tr("Contacts");
+   return QObject::tr("Contact");
 }
 
 QVariant FallbackPersonCollection::icon() const

src/private/collectionmodel_p.h

@@ -43,7 +43,7 @@ public:
     * index have to be implemented.
     */
    struct ProxyItem {
-      ProxyItem() : parent(nullptr),col(1),row(0),collection(nullptr),manageableCount(0){}
+      ProxyItem() : parent(nullptr),col(0),row(0),collection(nullptr),manageableCount(0){}
       int row;
       int col;
       CollectionInterface* collection;