chore(transactor): Fix nil pointer dereference issue (#81)

* Fix

* comment nit

core/transactor/loop.go

@@ -89,7 +89,7 @@ func (t *TxrV2) retrieveBatch(ctx context.Context) types.Requests {
 
 // fire processes the tracked tx response. If requested to build, it will first batch the messages.
 // Then it sends the batch as one tx and asynchronously tracks the tx for its status.
-// NOTE: if toBuild is false, resp.Transaction must be a valid, non-nil tx.
+// NOTE: if toBuild is false, resp.Transaction must be a valid, signed tx.
 func (t *TxrV2) fire(
 	ctx context.Context, resp *tracker.Response, toBuild bool, msgs ...*ethereum.CallMsg,
 ) {

core/transactor/tracker/response.go

@@ -3,6 +3,7 @@ package tracker
 import (
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
 	coretypes "github.com/ethereum/go-ethereum/core/types"
 )
 
@@ -20,21 +21,49 @@ type Response struct {
 }
 
 // Status returns the current status of a transaction owned by the transactor.
-func (t *Response) Status() Status {
-	if t.Error != nil {
+func (r *Response) Status() Status {
+	if r.Error != nil {
 		return StatusError
 	}
 
-	if t.receipt == nil {
-		if t.isStale {
+	if r.receipt == nil {
+		if r.isStale {
 			return StatusStale
 		}
 		return StatusPending
 	}
 
-	if t.receipt.Status == 1 {
+	if r.receipt.Status == 1 {
 		return StatusSuccess
 	}
 
 	return StatusReverted
 }
+
+// Nonce overrides the method on Transaction to avoid dereferencing a nil pointer.
+func (r *Response) Nonce() uint64 {
+	if r.Transaction != nil {
+		return r.Transaction.Nonce()
+	}
+
+	return 0
+}
+
+// To overrides the method on Transaction to avoid dereferencing a nil pointer.
+func (r *Response) To() *common.Address {
+	if r.Transaction != nil {
+		return r.Transaction.To()
+	}
+
+	zeroAddr := common.Address{}
+	return &zeroAddr
+}
+
+// Hash overrides the method on Transaction to avoid dereferencing a nil pointer.
+func (r *Response) Hash() common.Hash {
+	if r.Transaction != nil {
+		return r.Transaction.Hash()
+	}
+
+	return common.Hash{}
+}

core/transactor/tracker/tracker.go

@@ -154,17 +154,13 @@ func (t *Tracker) markPending(ctx context.Context, resp *Response) {
 	// Remove from the noncer inFlight set since we know the tx has reached the mempool as
 	// executable/pending.
 	t.noncer.RemoveInFlight(resp.Nonce())
-
 	t.waitMined(ctx, resp, true)
 }
 
 // markConfirmed is called once a transaction has been included in the canonical chain.
 func (t *Tracker) markConfirmed(resp *Response, receipt *coretypes.Receipt) {
 	// Set the contract address field on the receipt since geth doesn't do this.
-	if contractAddr := resp.To(); contractAddr != nil && receipt != nil {
-		receipt.ContractAddress = *contractAddr
-	}
-
+	receipt.ContractAddress = *resp.To()
 	resp.receipt = receipt
 	t.dispatchTx(resp)
 }