op-node: Fix OPB-10 (#3548)

* op-node: Fix OPB-10

Fixes OPB-10: No Checks for Deposit Transaction Type When Calling `L1InfoDepositTxData()`. This PR adds a check in `blockToBatch` that checks the type of the first transaction in the block, and returns an error if it isn't a deposit transaction.

* goimports
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

op-node/rollup/derive/channel_out.go

@@ -13,6 +13,8 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
+var ErrNotDepositTx = errors.New("first transaction in block is not a deposit tx")
+
 type ChannelOut struct {
 	id ChannelID
 	// Frame ID of the next frame to emit. Increment after emitting
@@ -153,6 +155,9 @@ func blockToBatch(block *types.Block, w io.Writer) error {
 		opaqueTxs = append(opaqueTxs, otx)
 	}
 	l1InfoTx := block.Transactions()[0]
+	if l1InfoTx.Type() != types.DepositTxType {
+		return ErrNotDepositTx
+	}
 	l1Info, err := L1InfoDepositTxData(l1InfoTx.Data())
 	if err != nil {
 		return err // TODO: wrap err

op-node/rollup/derive/channel_out_test.go

+package derive
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/stretchr/testify/require"
+)
+
+func TestChannelOutAddBlock(t *testing.T) {
+	cout, err := NewChannelOut()
+	require.NoError(t, err)
+
+	t.Run("returns err if first tx is not an l1info tx", func(t *testing.T) {
+		header := &types.Header{Number: big.NewInt(1), Difficulty: big.NewInt(100)}
+		block := types.NewBlockWithHeader(header).WithBody(
+			[]*types.Transaction{
+				types.NewTx(&types.DynamicFeeTx{}),
+			},
+			nil,
+		)
+		err := cout.AddBlock(block)
+		require.Error(t, err)
+		require.Equal(t, ErrNotDepositTx, err)
+	})
+}