Changed the FlashList using syntax according to the WebEditor errors (#2569)

Author: adids1221

src/incubator/Calendar/Agenda.tsx

@@ -9,7 +9,7 @@ import {isSameDay, isSameMonth} from './helpers/DateUtils';
 import {InternalEvent, Event, DateSectionHeader, UpdateSource} from './types';
 import CalendarContext from './CalendarContext';
 
-const {FlashList} = FlashListPackage;
+const FlashList = FlashListPackage?.FlashList;
 
 // TODO: Fix initial scrolling
 function Agenda() {

src/incubator/Calendar/index.tsx

@@ -13,7 +13,7 @@ import Agenda from './Agenda';
 import TodayButton from './TodayButton';
 import Header from './Header';
 
-const {FlashList} = FlashListPackage;
+const FlashList = FlashListPackage?.FlashList;
 
 // TODO: Move this logic elsewhere to pre-generate on install?
 const MONTH_ITEMS = generateMonthItems(2);