fixed warning message in device panel thanks to andrea

smart-hut/src/components/dashboard/DevicePanel.js

@@ -25,7 +25,7 @@ class DevicePanel extends Component {
   render() {
     return (
       <Card.Group centered style={{ paddingTop: "3rem" }}>
-        {this.props.devices.length !== 0 ? (
+        {this.props.numbeOfRooms > 0 ? (
           <React.Fragment>
             {this.props.devices.map((e, i) => {
               return <Device key={i} tab={this.props.tab} id={e.id} />;
@@ -70,6 +70,9 @@ const mapStateToProps = (state, _) => ({
     return state.active.activeRoom === -1;
   },
   activeRoom: state.active.activeRoom,
+  get numbeOfRooms() {
+    return Object.keys(state.rooms).length;
+  },
 });
 const DevicePanelContainer = connect(
   mapStateToProps,