op-program: Update goerli verification script to handle long safe head stalls

Uses the latest output if there isn't an output after the current finalized block and checks it's at or before the finalized block.

op-program/verify/cmd/goerli.go

@@ -56,6 +56,7 @@ func Run(l1RpcUrl string, l2RpcUrl string, l2OracleAddr common.Address) error {
 	if err != nil {
 		return fmt.Errorf("get l2 safe head: %w", err)
 	}
+	fmt.Printf("Found L2 finalized head number: %v hash: %v\n", l2FinalizedHead.NumberU64(), l2FinalizedHead.Hash())
 
 	// Find L1 finalized block. Can't be re-orged and must contain all batches for the L2 finalized block
 	l1BlockNum := big.NewInt(int64(rpc.FinalizedBlockNumber))
@@ -63,18 +64,28 @@ func Run(l1RpcUrl string, l2RpcUrl string, l2OracleAddr common.Address) error {
 	if err != nil {
 		return fmt.Errorf("find L1 head: %w", err)
 	}
+	fmt.Printf("Found l1 head block number: %v hash: %v\n", l1HeadBlock.NumberU64(), l1HeadBlock.Hash())
 
 	// Get the most published L2 output from before the finalized block
 	callOpts := &bind.CallOpts{Context: ctx}
 	outputIndex, err := outputOracle.GetL2OutputIndexAfter(callOpts, l2FinalizedHead.Number())
 	if err != nil {
-		return fmt.Errorf("get output index after finalized block: %w", err)
+		fmt.Println("Failed to get output index after finalized block. Checking latest output", "finalized", l2FinalizedHead.Number(), "err", err)
+		outputIndex, err = outputOracle.LatestOutputIndex(callOpts)
+		if err != nil {
+			return fmt.Errorf("get latest output index: %w", err)
+		}
+	} else {
+		outputIndex = outputIndex.Sub(outputIndex, big.NewInt(1))
 	}
-	outputIndex = outputIndex.Sub(outputIndex, big.NewInt(1))
 	output, err := outputOracle.GetL2Output(callOpts, outputIndex)
 	if err != nil {
 		return fmt.Errorf("retrieve latest output: %w", err)
 	}
+	// Check we wound up with an output prior to the finalized block
+	if output.L2BlockNumber.Uint64() > l2FinalizedHead.NumberU64() {
+		return fmt.Errorf("selected output is after finalized head output block: %v, finalized block: %v", output.L2BlockNumber.Uint64(), l2FinalizedHead.NumberU64())
+	}
 
 	l1Head := l1HeadBlock.Hash()
 	l2Claim := common.Hash(output.OutputRoot)