Push Notification not working in rocket chat 6.2.x

I have installed rocket chat server using snap packages and developed android or IOS Flutter app(Firebase messaging).

Integrated my required APIs of rocket chat, webhooks and used PUSH token POST API and send FCM token to roket chat server, Did configured my push config under settings->push. I am expecting to receive notification when app is closed but instead i see these logs

{"level":20,"time":"2023-07-13T11:43:06.331Z","pid":68726,"hostname":"chat","name":"Push","msg":"TypeError: Cannot read property 'send' of undefined<br>    at sendAPN (app/push/server/apn.js:48:16)<br>    at PushClass.sendNotificationNative (app/push/server/push.js:85:5)<br>    at app/push/server/push.js:213:16<br>    at /snap/rocketchat-server/1563/programs/server/npm/node_modules/meteor/npm-mongo/node_modules/mongodb/lib/cursor/abstract_cursor.js:245:32<br>    at runMicrotasks (<anonymous>)<br>    at processTicksAndRejections (internal/process/task_queues.js:95:5)<br> => awaited here:<br>    at Function.Promise.await (/snap/rocketchat-server/1563/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/promise_server.js:56:12)<br>    at app/push/server/push.js:206:3<br>    at /snap/rocketchat-server/1563/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/fiber_pool.js:43:40<br> => awaited here:<br>    at Function.Promise.await (/snap/rocketchat-server/1563/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/promise_server.js:56:12)<br>    at app/push/server/push.js:347:4<br>    at /snap/rocketchat-server/1563/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/fiber_pool.js:43:40"} 

Server Setup Information

Version: 6.2.9
Apps Engine Version: 1.39.1
Node Version: v14.21.2
Database Migration: 294 (July 7, 2023 5:54 PM)
MongoDB: 5.0.15 / wiredTiger (oplog Enabled)

If i click on test notification button under settings->push it says “There are no tokens for this user”.