Add more logging information to monotonicity violation logs (#1066)

* refactor: log idx of monotonicity violation from batch

* build: add changeset

.changeset/weak-terms-worry.md

+---
+'@eth-optimism/batch-submitter': patch
+---
+
+Log additional data in monotonicity violation

packages/batch-submitter/src/batch-submitter/tx-batch-submitter.ts

@@ -356,13 +356,17 @@ export class TransactionBatchSubmitter extends BatchSubmitter {
     // Verify all of the batch elements are monotonic
     let lastTimestamp: number
     let lastBlockNumber: number
-    for (const ele of batch) {
+    for (const [idx, ele] of batch.entries()) {
       if (ele.timestamp < lastTimestamp) {
-        this.logger.error('Timestamp monotonicity violated! Element', { ele })
+        this.logger.error('Timestamp monotonicity violated! Element', {
+          idx,
+          ele,
+        })
         return false
       }
       if (ele.blockNumber < lastBlockNumber) {
         this.logger.error('Block Number monotonicity violated! Element', {
+          idx,
           ele,
         })
         return false