tg.Update.Msg() method doesn't cover all cases

[mineroot]

Example with session.Manager + tgb.Router.MessageReaction()

router := tgb.NewRouter().
Use(sessionManager). // *session.Manager[T]
Message(func(ctx context.Context, msg *tgb.MessageUpdate) error {
	// this works

	// TODO...
	return nil
}).
MessageReaction(func(ctx context.Context, reaction *tgb.MessageReactionUpdate) error {
	// this doesn't work 
        // as session.Manager.Wrap() returns an error "can't get key from update" 

	// TODO...
	return nil
})

session.Manager.Wrap() returns an error because of its default session.KeyFuncChat() which calls tg.Update.Msg() method (not directly)

// Msg returns message from whever possible.
// It returns nil if message is not found.
func (update *Update) Msg() *Message {
	switch {
	case update == nil:
		return nil
	case update.Message != nil:
		return update.Message
	case update.EditedMessage != nil:
		return update.EditedMessage
	case update.ChannelPost != nil:
		return update.ChannelPost
	case update.EditedChannelPost != nil:
		return update.EditedChannelPost
	case update.CallbackQuery != nil && update.CallbackQuery.Message != nil && update.CallbackQuery.Message.Message != nil:
		return update.CallbackQuery.Message.Message
	case update.BusinessMessage != nil:
		return update.BusinessMessage
	case update.EditedBusinessMessage != nil:
		return update.EditedBusinessMessage
	default:
		return nil
	}
}

this method do not cover update.MessageReaction, MessageReactionCount (and probably some other types which can return Chat field needed for session.KeyFuncChat())

So, @mr-linch, is this a bug, or this is intentional? This also can be fixed by passing custom KeyFunc which handles all cases...

What do you think?

BTW, thanks for the great package!