feat: Prevent users from starting levels that they did not reach yet

frontend/src/reducers/index.ts

@@ -34,6 +34,7 @@ interface IState {
 
     levelList: {
         loading: boolean;
+        snackbar: boolean;
     };
 
     dashboard: {
@@ -91,6 +92,7 @@ const initialState: IState = {
 
     levelList: {
         loading: true,
+        snackbar: false,
     },
 
     dashboard: {
@@ -248,6 +250,12 @@ export function LateinicusApp(state: IState = initialState, action: any) {
                     loading: action.state,
                 }),
             });
+        case Actions.LEVELLIST_SET_SNACKBAR:
+            return Object.assign({}, state, {
+                levelList: Object.assign({}, state.levelList, {
+                    snackbar: action.state,
+                }),
+            });
         default:
             // Ignore the initialization call to the reducer. By that we can
             // catch all actions that are not implemented