Log error instead of warning when failing to instantiate node instance

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Views/MaterialGraphView.cs

             }
             catch (Exception e)
             {
-                Debug.LogWarningFormat("Could not construct instance of: {0} - {1}", posObj.m_Type, e);
+                Debug.LogErrorFormat("Could not construct instance of: {0} - {1}", posObj.m_Type, e);
                 return;
             }