fix ProcessPendingBundles record not found (#1444)

Author: georgehao

rollup/internal/controller/relayer/l2_relayer.go

@@ -505,10 +505,14 @@ func (r *Layer2Relayer) ProcessPendingBundles() {
 	r.metrics.rollupL2RelayerProcessPendingBundlesTotal.Inc()
 
 	bundle, err := r.bundleOrm.GetFirstPendingBundle(r.ctx)
+	if bundle == nil && err == nil {
+		return
+	}
 	if err != nil {
 		log.Error("Failed to fetch first pending L2 bundle", "err", err)
 		return
 	}
+
 	status := types.ProvingStatus(bundle.ProvingStatus)
 	switch status {
 	case types.ProvingTaskUnassigned, types.ProvingTaskAssigned:

rollup/internal/orm/bundle.go

@@ -126,6 +126,9 @@ func (o *Bundle) GetFirstPendingBundle(ctx context.Context) (*Bundle, error) {
 
 	var pendingBundle Bundle
 	if err := db.First(&pendingBundle).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, nil
+		}
 		return nil, fmt.Errorf("Bundle.GetFirstPendingBundle error: %w", err)
 	}
 	return &pendingBundle, nil