Reinstate 'backfeed channel full' error.

main.go

@@ -77,8 +77,8 @@ func (that *ProjectBackfeedManager) PushItem(ctx context.Context, item *Backfeed
 		return fmt.Errorf("backfeed channel closed")
 	case that.C <- item:
 		return nil
-		//default:
-		//	return fmt.Errorf("backfeed channel full")
+	default:
+		return fmt.Errorf("backfeed channel full")
 	}
 }