Code 4006 Session Error

[croxydev]

When the bot enter the voice channel for the first time, it giving the following error:
{
op: 'event',
reason: 'Session is no longer valid.',
code: 4006,
byRemote: true,
type: 'WebSocketClosedEvent',
guildId: '652877747621986348'
}

After this error, I turn the bot off and on and when I enter the command to play music again, the music plays successfully. But after the bot exits from the voice channel and enters the music command again, this error occurs again.

[TristanWasTaken]

The code 4006 means that the bot didn't exit the voice channel correctly. Discord gives voice connections a session ID.
If the bot times out or disconnects from the gateway, Discord assumes the connection is inactive and that your bot will try to connect with a new session id.
When your bot connects to a voice channel, it should replace the old session ID with a new one (see Manager.ts).

It works if you restart your bot because you kill your bot process and delete the cached connection id with it. I assume it should be a bug in your bot.