Fixing compiler warnings (compiled with IAR and configured for no printing)

bacnet-stack/demo/handler/h_wp.c

@@ -137,8 +137,11 @@ void handler_write_property(
         datalink_send_pdu(src, &npdu_data, &Handler_Transmit_Buffer[0],
         pdu_len);
 #if PRINT_ENABLED
-    if (bytes_sent <= 0)
+    if (bytes_sent <= 0) {
         fprintf(stderr, "WP: Failed to send PDU (%s)!\n", strerror(errno));
+    }
+#else
+    bytes_sent = bytes_sent;
 #endif
 
     return;