Fix a potential crash when disconnecting older setups

libnymea-app/energy/energylogs.cpp

@@ -48,16 +48,17 @@ void EnergyLogs::setEngine(Engine *engine)
         if (!m_engine) {
             return;
         }
+
+        connect(engine, &Engine::destroyed, this, [=](){
+            if (engine == m_engine) {
+                m_engine = nullptr;
+                emit engineChanged();
+            }
+        });
+
         if (m_engine->jsonRpcClient()->experiences().value("Energy").toString() >= "1.0") {
             m_engine->jsonRpcClient()->registerNotificationHandler(this, "Energy", "notificationReceivedInternal");
 
-            connect(engine, &Engine::destroyed, this, [=](){
-                if (engine == m_engine) {
-                    m_engine = nullptr;
-                    emit engineChanged();
-                }
-            });
-
             if (m_ready && !m_loadingInhibited) {
                 fetchLogs();
             }

libnymea-app/energy/energylogs.h

@@ -49,7 +49,7 @@ public:
     Q_ENUM(SampleRate)
 
     explicit EnergyLogs(QObject *parent = nullptr);
-    ~EnergyLogs();
+    virtual ~EnergyLogs();
 
     Engine *engine() const;
     void setEngine(Engine *engine);