Stack: Only destroy mdns if initialized

src/server/ua_discovery_manager.c

@@ -72,11 +72,12 @@ initMulticastDiscoveryServer(UA_DiscoveryManager *dm, UA_Server* server) {
 
 static void
 destroyMulticastDiscoveryServer(UA_DiscoveryManager *dm) {
-    if(dm->mdnsDaemon)
-    {
-        mdnsd_shutdown(dm->mdnsDaemon);
-        mdnsd_free(dm->mdnsDaemon);
-    }
+	if (!dm->mdnsDaemon)
+		return;
+
+	mdnsd_shutdown(dm->mdnsDaemon);
+	mdnsd_free(dm->mdnsDaemon);
+
     if(dm->mdnsSocket != UA_INVALID_SOCKET) {
         UA_close(dm->mdnsSocket);
         dm->mdnsSocket = UA_INVALID_SOCKET;