chore: do not reassign result

Author: stfsy

lib/index.js

@@ -344,7 +344,7 @@ class Subscriptions {
         return payments //
             .sort((a, b) => new Date(a.event_time).getTime() - new Date(b.event_time).getTime())
             .map(payment => {
-                let result = {
+                const result = {
                     event_time: payment.event_time,
                     description: payment.alert_name,
                     amount: {
@@ -356,14 +356,14 @@ class Subscriptions {
                     subscription_plan_id: payment.subscription_plan_id,
                 }
                 if (payment.alert_name === 'subscription_payment_failed') {
-                    result = Object.assign(result, {
+                    Object.assign(result, {
                         next_try: {
                             date: payment.next_retry_date
                         },
                         instalments: payment.instalments,
                     })
                 } else if (payment.alert_name === 'subscription_payment_refunded') {
-                    result = Object.assign(result, {
+                    Object.assign(result, {
                         refund: {
                             reason: payment.refund_reason,
                             type: payment.refund_type
@@ -372,7 +372,7 @@ class Subscriptions {
                     })
                     result.amount.total = payment.gross_refund
                 } else if (payment.alert_name === 'subscription_payment_succeeded') {
-                    result = Object.assign(result, {
+                    Object.assign(result, {
                         next_payment: {
                             date: payment.next_bill_date,
                             amount: {