Aggregation: Fix crash when components are in parent-child relationship

and the child is deleted first.

Change-Id: Idea3b4a3410bda99a8727551e2cbeab3a7b95d85
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/libs/aggregation/aggregate.cpp

@@ -193,6 +193,9 @@ void Aggregate::deleteSelf(QObject *obj)
         QWriteLocker locker(&lock());
         aggregateMap().remove(obj);
         m_components.removeAll(obj);
+        // Avoid issues if obj was child of another component of the aggregate.
+        // The parent is deleted in ~Aggregate and might still have a reference on obj
+        obj->setParent({});
     }
     delete this;
 }