Fix Undefined variable notice

sections/store/index.php

@@ -14,8 +14,10 @@ if (isset($_GET['api']) && $_GET['api'] == 1) {
     list($Purchases, $Price) = [0, 1000];
   }
 
-  $Response->purchases = $Purchases;
-  $Response->price = $Price;
+  $Response = array(
+    "purchases" => $Purchases,
+    "price" => $Price,
+  );
   echo json_encode($Response);
 
 } else {