The payload of :guild_delete. unavailable is true when the guild is
down in an outage (it comes back with a :guild_create), and false when
the bot left or was removed. old is the guild as cached, or nil.
Summary
Types
@type t() :: %Lingo.Event.GuildDelete{ id: String.t(), old: Lingo.Type.Guild.t() | nil, unavailable: boolean() }