Undefd prop: stdClass::$created (line 236 uc_shipstation.module)

My logs reported the following error when refreshing my order list in ShipStation:

Notice: Undefined property: stdClass::$created in uc_shipstation_export_orders() (line 236 of /var/www/html/pethub.com/sites/all/modules/uc_shipstation/uc_shipstation.module).

In addition, the orders all showed an Order Date of 12/31/1969.

Line 236 has the following line of code:
$order_date = $transaction->created;

Changing it to the following had the desired effect:
$order_date = $transaction->received;