fix race condition: DB_READY lost when utun thread starts before gui_bridge_init

- mainwindow.cpp: swap setupMessaging() before setupNode() so g_receiver is created first
- gui_bridge_impl.cpp: add DEBUG_WARN when gui_bridge_post drops event due to NULL g_receiver

tools/chatgui/src/mainwindow.cpp

@@ -102,8 +102,8 @@ MainWindow::MainWindow(QWidget *parent, DbManager* db, const QString& cfgPath,
             }
         });
 
-        setupNode();
         setupMessaging();
+        setupNode();
 
         connect(m_channelList, &ChannelList::channelSelected,
                 this, [this](const QString& channelId) {