[ws] Accessing list of unavailable guilds when shard turns ready

In @discordjs/ws, how am i supposed to access the list of unavailable guilds after a shard becomes ready? The ready event on WebSocketShard is hidden away and the ready even on WebSocketManager doesnt supply me with the data i want. The reason i want the list of unavailable guilds is so that i can use these when receiving GUILD_CREATEs to know whether something is a new guild or simply a guild becoming available