From 895cb81f0fd10a6f9aa8bb02146225db2119020c Mon Sep 17 00:00:00 2001
From: Mark Tyneway <mark.tyneway@gmail.com>
Date: Wed, 21 Apr 2021 18:01:47 -0700
Subject: [PATCH] l2geth: fix error handling for get tx batch

---
 l2geth/rollup/client.go       |  4 ++--
 l2geth/rollup/sync_service.go | 28 +++++++++++++++-------------
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/l2geth/rollup/client.go b/l2geth/rollup/client.go
index d44fbf2c8ede..26241f4e821c 100644
--- a/l2geth/rollup/client.go
+++ b/l2geth/rollup/client.go
@@ -548,8 +548,8 @@ func (c *Client) GetTransactionBatch(index uint64) (*Batch, []*types.Transaction
 // parseTransactionBatchResponse will turn a TransactionBatchResponse into a
 // Batch and its corresponding types.Transactions
 func parseTransactionBatchResponse(txBatch *TransactionBatchResponse, signer *types.OVMSigner) (*Batch, []*types.Transaction, error) {
-	if txBatch == nil {
-		return nil, nil, nil
+	if txBatch == nil || txBatch.Batch == nil {
+		return nil, nil, errElementNotFound
 	}
 	batch := txBatch.Batch
 	txs := make([]*types.Transaction, len(txBatch.Transactions))
diff --git a/l2geth/rollup/sync_service.go b/l2geth/rollup/sync_service.go
index 628f1045a733..cce4a6fd03dd 100644
--- a/l2geth/rollup/sync_service.go
+++ b/l2geth/rollup/sync_service.go
@@ -669,13 +669,13 @@ func (s *SyncService) syncTransactionsToTip(backend Backend) error {
 
 	for {
 		latest, err := s.client.GetLatestTransaction(backend)
-		if err != nil {
-			return fmt.Errorf("Cannot get latest transaction: %w", err)
-		}
-		if latest == nil {
+		if errors.Is(err, errElementNotFound) {
 			log.Info("No transactions to sync")
 			return nil
 		}
+		if err != nil {
+			return fmt.Errorf("Cannot get latest transaction: %w", err)
+		}
 		latestIndex := latest.GetMeta().Index
 		if latestIndex == nil {
 			return errors.New("Latest index is nil")
@@ -722,13 +722,13 @@ func (s *SyncService) syncTransactionBatchesToTip() error {
 
 	for {
 		latest, _, err := s.client.GetLatestTransactionBatch()
-		if err != nil {
-			return fmt.Errorf("Cannot get latest transaction batch: %w", err)
-		}
-		if latest == nil {
+		if errors.Is(err, errElementNotFound) {
 			log.Info("No transaction batches to sync")
 			return nil
 		}
+		if err != nil {
+			return fmt.Errorf("Cannot get latest transaction batch: %w", err)
+		}
 		latestIndex := latest.Index
 		nextIndex := s.GetNextVerifiedIndex()
 
@@ -739,7 +739,9 @@ func (s *SyncService) syncTransactionBatchesToTip() error {
 				return fmt.Errorf("Cannot get transaction batch: %w", err)
 			}
 			for _, tx := range txs {
-				s.applyBatchedTransaction(tx)
+				if err := s.applyBatchedTransaction(tx); err != nil {
+					return fmt.Errorf("cannot apply batched transaction: %w", err)
+				}
 			}
 		}
 		post, _, err := s.client.GetLatestTransactionBatch()
@@ -760,13 +762,13 @@ func (s *SyncService) syncQueueToTip() error {
 
 	for {
 		latest, err := s.client.GetLatestEnqueue()
-		if err != nil {
-			return fmt.Errorf("Cannot get latest enqueue transaction: %w", err)
-		}
-		if latest == nil {
+		if errors.Is(err, errElementNotFound) {
 			log.Info("No enqueue transactions to sync")
 			return nil
 		}
+		if err != nil {
+			return fmt.Errorf("Cannot get latest enqueue transaction: %w", err)
+		}
 		latestIndex := latest.GetMeta().QueueIndex
 		if latestIndex == nil {
 			return errors.New("Latest queue transaction has no queue index")