When I tried using Heroku to host my bot building went fine but an error code popped up:

2021-09-20T08:42:36.380205+00:00 heroku[worker.1]: Starting process with command `node index.js`
2021-09-20T08:42:37.212184+00:00 heroku[worker.1]: State changed from starting to up
2021-09-20T08:42:37.856773+00:00 heroku[worker.1]: Process exited with status 0
2021-09-20T08:42:37.718428+00:00 app[worker.1]: (node:4) UnhandledPromiseRejectionWarning: ReferenceError: AbortController is not defined
2021-09-20T08:42:37.718449+00:00 app[worker.1]:     at RequestHandler.execute (/app/node_modules/discord.js/src/rest/RequestHandler.js:172:15)
2021-09-20T08:42:37.718449+00:00 app[worker.1]:     at RequestHandler.execute (/app/node_modules/discord.js/src/rest/RequestHandler.js:176:19)
2021-09-20T08:42:37.718449+00:00 app[worker.1]:     at RequestHandler.push (/app/node_modules/discord.js/src/rest/RequestHandler.js:50:25)
2021-09-20T08:42:37.718452+00:00 app[worker.1]:     at async WebSocketManager.connect (/app/node_modules/discord.js/src/client/websocket/WebSocketManager.js:128:9)
2021-09-20T08:42:37.718452+00:00 app[worker.1]:     at async Client.login (/app/node_modules/discord.js/src/client/Client.js:245:7)
2021-09-20T08:42:37.722717+00:00 app[worker.1]: (Use `node --trace-warnings ...` to show where the warning was created)
2021-09-20T08:42:37.722735+00:00 app[worker.1]: (node:4) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
2021-09-20T08:42:37.722739+00:00 app[worker.1]: (node:4) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.``` 
After then somebody suggested me that its a version error so I added the code: ```"engines": {
    "node": "16.7.0"
  }

and when I tried to build it, it now fails, any help?