Base: fixes #10462: mesh.unite() causes segementaion fault

src/Base/Builder3D.cpp

@@ -955,7 +955,8 @@ void InventorBuilder::endSeparator()
  * A more elaborate description of the constructor.
  */
 Builder3D::Builder3D()
-  : InventorBuilder(result)
+  : result{}
+  , builder{result}
 {
 }
 
@@ -1008,6 +1009,21 @@ void Builder3D::saveToFile(const char* FileName)
     file << result.str();
 }
 
+void Builder3D::addNode(const NodeItem& item)
+{
+    builder.addNode(item);
+}
+
+void Builder3D::beginSeparator()
+{
+    builder.beginSeparator();
+}
+
+void Builder3D::endSeparator()
+{
+    builder.endSeparator();
+}
+
 // -----------------------------------------------------------------------------
 
 template<typename T>