Fix: Check if valid data was received from websocket before assigning it

Otherwise it can lead to exceptions in inverterData method

webapp/src/views/HomeView.vue

@@ -485,7 +485,9 @@ export default defineComponent({
 
             this.socket.onmessage = (event) => {
                 console.log(event);
+                if (event.data != "{}") {
                     this.liveData = JSON.parse(event.data);
+                }
                 this.dataLoading = false;
                 this.heartCheck(); // Reset heartbeat detection
             };