feat: new RollbackOnError method added for transactional db helper and integrated into auth service

backend/internal/database/helper.go

@@ -26,6 +26,7 @@ import (
 type DbHelperTransaction interface {
 	Commit() error
 	Rollback() error
+	RollbackOnError(err error) error
 }
 
 type DbHelper struct {
@@ -98,3 +99,11 @@ func (d *dbHelperTransactionImpl) Rollback() error {
 	}
 	return nil
 }
+
+// RollbackOnError implements DbHelperTransaction.
+func (d *dbHelperTransactionImpl) RollbackOnError(err error) error {
+	if err != nil {
+		return d.Rollback()
+	}
+	return nil
+}

backend/internal/services/auth.go

@@ -66,7 +66,7 @@ func (a *authServiceImpl) RegistrationBegin(request models.RegistrationBeginRequ
 	var err error
 
 	helper, db, _ := database.NewDbHelperTransaction(a.dbctx)
-  defer helper.Rollback()
+  defer helper.RollbackOnError(err)
 
 	// TODO: check occupation with redis
 
@@ -199,7 +199,7 @@ func (a *authServiceImpl) RegistrationComplete(request models.RegistrationComple
 	var err error
 
 	helper, db, _ := database.NewDbHelperTransaction(a.dbctx)
-	defer helper.Rollback()
+	defer helper.RollbackOnError(err)
 
 	user, err = db.TXQueries.GetUserByUsername(db.CTX, request.Username)
 
@@ -334,11 +334,10 @@ func (a *authServiceImpl) RegistrationComplete(request models.RegistrationComple
 func (a *authServiceImpl) Login(request models.LoginRequest) (*models.LoginResponse, error) {
 	var userRow database.GetValidUserByLoginCredentialsRow
 	var session database.Session
+	var err error
 
 	helper, db, _ := database.NewDbHelperTransaction(a.dbctx)
-  defer helper.Rollback()
-
-	var err error
+  defer helper.RollbackOnError(err)
 
 	userRow, err = db.TXQueries.GetValidUserByLoginCredentials(db.CTX, database.GetValidUserByLoginCredentialsParams{
 		Username: request.Username,
@@ -417,7 +416,7 @@ func (a *authServiceImpl) PasswordResetBegin(request models.PasswordResetBeginRe
 	var err error
 
 	helper, db, err := database.NewDbHelperTransaction(a.dbctx)
-	defer helper.Rollback()
+	defer helper.RollbackOnError(err)
 
 	ctx := context.TODO()