No $charge->fee field returned by Stripe

Stripe was not returning the fee with recurring payments, so this was causing 500 error.

CRM/Stripe/Page/Webhook.php

@@ -85,7 +85,7 @@ class CRM_Stripe_Page_Webhook extends CRM_Core_Page {
         $stripe_customer = Stripe_Customer::retrieve($customer_id);
         $recieve_date = date("Y-m-d H:i:s", $charge->created);
         $total_amount = $charge->amount / 100;
-        $fee_amount = $charge->fee / 100;
+        $fee_amount = isset($charge->fee) ? ($charge->fee / 100) : 0;
         $net_amount = $total_amount - $fee_amount;
         $transaction_id = $charge->id;
         $new_invoice_id = $stripe_event_data->data->object->id;
@@ -215,7 +215,7 @@ class CRM_Stripe_Page_Webhook extends CRM_Core_Page {
         // Build some params.
         $recieve_date = date("Y-m-d H:i:s", $charge->created);
         $total_amount = $charge->amount / 100;
-        $fee_amount = $charge->fee / 100;
+        $fee_amount = isset($charge->fee) ? ($charge->fee / 100) : 0;
         $net_amount = $total_amount - $fee_amount;
         $transaction_id = $charge->id;
         if (empty($recur_contrib_query->campaign_id)) {