#3413 for master (#3414)

* Fix crash when NGRAPH_ENABLE_{VISUALIZE,SERIALIZE}_TRACING=1

* Initialization for kw

src/ngraph/op/topk.hpp

@@ -90,7 +90,7 @@ namespace ngraph
             size_t m_top_k_axis{0};
             element::Type m_index_element_type;
             bool m_compute_max{false};
-            SortType m_sort;
+            SortType m_sort{SortType::NONE};
             virtual void generate_adjoints(autodiff::Adjoints& adjoints,
                                            const NodeVector& deltas) override;
         };