Make sure getSettings() always returns settings or error

bot/mailbox.go

@@ -48,7 +48,7 @@ func (b *Bot) getMailbox(ctx context.Context, evt *event.Event) {
 	defer span.Finish()
 
 	cfg, err := b.getSettings(span.Context(), evt.RoomID)
-	if err != nil || cfg == nil {
+	if err != nil {
 		b.log.Warn("cannot get %s settings: %v", evt.RoomID, err)
 	}
 
@@ -83,9 +83,6 @@ func (b *Bot) setMailbox(ctx context.Context, evt *event.Event, mailbox string)
 	if err != nil {
 		b.log.Warn("cannot get settings: %v", err)
 	}
-	if cfg == nil {
-		cfg = &settings{}
-	}
 
 	if !cfg.Allowed(b.noowner, evt.Sender) {
 		b.Error(span.Context(), evt.RoomID, "you don't have permission to do that")