fix TS in Vew demos

Author: GoodDayForSurf

apps/demos/Demos/PivotGrid/IntegratedFieldChooser/Vue/App.vue

@@ -40,7 +40,7 @@ import {
   DxSelectBox,
 } from 'devextreme-vue/select-box';
 
-const dataSource = {
+const dataSource: Record<string, any> = {
   fields: [
     { dataField: '[Product].[Category]', area: 'row' },
     {

apps/demos/Demos/Scheduler/ContextMenu/Vue/App.vue

@@ -48,7 +48,7 @@ const appointmentClassName = '.dx-scheduler-appointment';
 const cellClassName = '.dx-scheduler-date-table-cell';
 const currentDate = ref(new Date(2020, 10, 25));
 const dataSource = data;
-const groups = ref<string[] | null>();
+const groups = ref<string[]>();
 const crossScrollingEnabled = ref(false);
 const disabled = ref(true);
 const contextMenuItems = ref<DxContextMenuTypes.Item[]>([]);
@@ -117,7 +117,7 @@ function onCellContextMenu({ cellData }: DxSchedulerTypes.CellContextMenuEvent)
       onItemClick: () => {
         if (groups.value) {
           crossScrollingEnabled.value = false;
-          groups.value = null;
+          groups.value = undefined;
         } else {
           crossScrollingEnabled.value = true;
           groups.value = ['roomId'];