refactor error handling in vat, cat, vow

pkg/transformers/vat_grab/repository.go

@@ -2,6 +2,7 @@ package vat_grab
 
 import (
 	"fmt"
+	"log"
 
 	"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
 	"github.com/vulcanize/vulcanizedb/pkg/transformers/shared"
@@ -13,31 +14,40 @@ type VatGrabRepository struct {
 }
 
 func (repository VatGrabRepository) Create(headerID int64, models []interface{}) error {
-	tx, err := repository.db.Begin()
-	if err != nil {
-		return err
+	tx, dBaseErr := repository.db.Begin()
+	if dBaseErr != nil {
+		return dBaseErr
 	}
 	for _, model := range models {
 		vatGrab, ok := model.(VatGrabModel)
 		if !ok {
-			tx.Rollback()
+			rollbackErr := tx.Rollback()
+			if rollbackErr != nil {
+				log.Println("failed to rollback ", rollbackErr)
+			}
 			return fmt.Errorf("model of type %T, not %T", model, VatGrabModel{})
 		}
 
-		_, err = tx.Exec(
+		_, execErr := tx.Exec(
 			`INSERT into maker.vat_grab (header_id, ilk, urn, v, w, dink, dart, log_idx, tx_idx, raw_log)
 	   VALUES($1, $2, $3, $4, $5, $6::NUMERIC, $7::NUMERIC, $8, $9, $10)`,
 			headerID, vatGrab.Ilk, vatGrab.Urn, vatGrab.V, vatGrab.W, vatGrab.Dink, vatGrab.Dart, vatGrab.LogIndex, vatGrab.TransactionIndex, vatGrab.Raw,
 		)
-		if err != nil {
-			tx.Rollback()
-			return err
+		if execErr != nil {
+			rollbackErr := tx.Rollback()
+			if rollbackErr != nil {
+				log.Println("failed to rollback ", rollbackErr)
+			}
+			return execErr
 		}
 	}
-	err = shared.MarkHeaderCheckedInTransaction(headerID, tx, constants.VatGrabChecked)
-	if err != nil {
-		tx.Rollback()
-		return err
+	checkHeaderErr := shared.MarkHeaderCheckedInTransaction(headerID, tx, constants.VatGrabChecked)
+	if checkHeaderErr != nil {
+		rollbackErr := tx.Rollback()
+		if rollbackErr != nil {
+			log.Println("failed to rollback ", rollbackErr)
+		}
+		return checkHeaderErr
 	}
 	return tx.Commit()
 }