refactor: move reward error transaction hash parsing

This commit moves the transaction hash parsing into the `rewardCallError`
method to keep all code related to the reward call error in one place.

eth/rewardservice.go

@@ -3,7 +3,6 @@ package eth
 import (
 	"context"
 	"fmt"
-	"strings"
 	"sync"
 
 	"github.com/ethereum/go-ethereum/core/types"
@@ -59,12 +58,8 @@ func (s *RewardService) Start(ctx context.Context) error {
 				tx, err := s.tryReward()
 				if err != nil {
 					glog.Errorf("Error trying to call reward err=%q", err)
-					var txHash string
-					if tx != nil && !strings.Contains(err.Error(), "context deadline exceeded") {
-						txHash = tx.Hash().Hex()
-					}
 					if monitor.Enabled {
-						monitor.RewardCallError(ctx, err.Error(), s.tw.LastInitializedRound(), txHash)
+						monitor.RewardCallError(ctx, err.Error(), s.tw.LastInitializedRound(), tx)
 					}
 				}
 			}()

monitor/census.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/golang/glog"
 	"github.com/livepeer/go-livepeer/clog"
 	lpnet "github.com/livepeer/go-livepeer/net"
@@ -1703,7 +1704,11 @@ func TranscodingPrice(sender string, price *big.Rat) {
 }
 
 // RewardCallError records an error from reward calling
-func RewardCallError(ctx context.Context, err string, round *big.Int, txHash string) {
+func RewardCallError(ctx context.Context, err string, round *big.Int, tx *types.Transaction) {
+	var txHash string
+	if tx != nil && !strings.Contains(err, "context deadline exceeded") {
+		txHash = tx.Hash().Hex()
+	}
 
 	var errCode string
 	if strings.Contains(err, "current round is not initialized") {