diff --git a/rpc/rpc.go b/rpc/rpc.go
index e40e938..0b9dc08 100644
--- a/rpc/rpc.go
+++ b/rpc/rpc.go
@@ -296,6 +296,9 @@ func (rpc *RPC) TransactionReceipt(ctx context.Context, txHash ethcommon.Hash) (
 		if err != nil {
 			return nil, err
 		}
+		if receipt == nil {
+			return nil, errors.New("transaction has no receipt")
+		}
 		return receipt, nil
 	}, 3, 100*time.Millisecond) // 3 retries with 100ms initial delay
 }
diff --git a/server/l2/block_inspector.go b/server/l2/block_inspector.go
index fdf5478..a45ff0d 100644
--- a/server/l2/block_inspector.go
+++ b/server/l2/block_inspector.go
@@ -756,7 +756,7 @@ func (bi *BlockInspector) processBlock(ctx context.Context, blockNumber uint64)
 				dropped := 0
 				for _, flashblocks := range payloads {
 					dropped += len(flashblocks)
-					for idx := len(flashblocks); idx >= 0; idx-- {
+					for idx := len(flashblocks) - 1; idx >= 0; idx-- {
 						fb := flashblocks[idx]
 						if fb != nil {
 							l.Warn("Flashblock was dropped",