client.voice.onVoiceStateUpdate is not a function - DiscordJS - node.js

Question

I've been experiencing this issue for a while now; my bot was working perfectly fine about a week ago.
I'm running the latest NodeJS (15.5.1) and Discord.JS (12.5.1) and Erela.js (2.3.1)
I've tried reinstalling all of them with still the return issue (below),
I've asked more than 10 times in the Official Discord.JS server with no avail,
I've asked in the Erela.js Official Discord (awaiting reply)
I'm completely out of ideas as to why I am getting this issue, theres literally nothing with my code as it worked fine, and was running on the latest modules (described above erela.js & discord.js)
Now all of a sudden approx. a week ago now, this issue appeared and I've been trying to troubleshoot it ever since discovering the issue.
I have provided the full stacktrace below along with link to the exact file from discord.js src:
Discord.JS Repo - VoiceStateUpdate.js
[2:57:49 PM] ERROR [Uncaught Exception]: TypeError: client.voice.onVoiceStateUpdate is not a function
at VoiceStateUpdate.handle
(/home/thewarden/node_modules/discord.js/src/client/actions/VoiceStateUpdate.js:31:22)
at Object.module.exports [as VOICE_STATE_UPDATE]
(/home/thewarden/node_modules/discord.js/src/client/websocket/handlers/VOICE_STATE_UPDATE.js:4:35)
at WebSocketManager.handlePacket
(/home/thewarden/node_modules/discord.js/src/client/websocket/WebSocketManager.js:384:31)
at WebSocketShard.onPacket
(/home/thewarden/node_modules/discord.js/src/client/websocket/WebSocketShard.js:444:22)
at WebSocketShard.onMessage
(/home/thewarden/node_modules/discord.js/src/client/websocket/WebSocketShard.js:301:10)
at WebSocket.onMessage (/home/thewarden/node_modules/ws/lib/event-target.js:132:16)
at WebSocket.emit (node:events:376:20)
at Receiver.receiverOnMessage (/home/thewarden/node_modules/ws/lib/websocket.js:825:20)
at Receiver.emit (node:events:376:20)
at Receiver.dataMessage (/home/thewarden/node_modules/ws/lib/receiver.js:437:14)
at Receiver.getData (/home/thewarden/node_modules/ws/lib/receiver.js:367:17)
at Receiver.startLoop (/home/thewarden/node_modules/ws/lib/receiver.js:143:22)
at Receiver._write (/home/thewarden/node_modules/ws/lib/receiver.js:78:10)
at writeOrBuffer (node:internal/streams/writable:395:12)
at Receiver.Writable.write (node:internal/streams/writable:340:10)
at TLSSocket.socketOnData (/home/thewarden/node_modules/ws/lib/websocket.js:900:35)

Answer 1

voiceStateUpdate is an event. To run it, you'll need to use the client.on()function that calls an event, with the correct callback.
Therefore, your code should look like the following:
client.on('voiceStateUpdate', oldState, newState => {
// code here
})
To learn more about the voiceStateUpdate event and its callback: https://discord.js.org/#/docs/main/stable/class/Client?scrollTo=e-voiceStateUpdate