fix objecttype initialization

src/server/ua_nodes.c

@@ -171,7 +171,7 @@ void UA_ObjectTypeNode_init(UA_ObjectTypeNode *p) {
 	UA_Node_init((UA_Node*)p);
     p->nodeClass = UA_NODECLASS_OBJECTTYPE;
     p->isAbstract = UA_FALSE;
-    p->instanceManagement = (UA_ObjectInstanceManagement){UA_NULL};
+    p->instanceManagement = (UA_ObjectInstanceManagement){.constructor = UA_NULL, .destructor = UA_NULL};
 }
 
 UA_ObjectTypeNode * UA_ObjectTypeNode_new(void) {