Merge pull request #68 from Nacoma/master

Prevent invalid array access _ thanks @Nacoma

Author: jfriedr

lib/Shippo/Util.php

@@ -12,15 +12,15 @@ public static function isList($array)
     {
         if (!is_array($array))
             return false;
-        
+
         // TODO: generally incorrect, but it's correct given Shippo's response
         foreach (array_keys($array) as $k) {
             if (!is_numeric($k))
                 return false;
         }
         return true;
     }
-    
+
     /**
      * Recursively converts the PHP Shippo object to an array.
      *
@@ -32,7 +32,7 @@ public static function convertShippoObjectToArray($values)
         $results = array();
         foreach ($values as $k => $v) {
             // FIXME: this is an encapsulation violation
-            if ($k[0] == '_') {
+            if (is_string($k) && $k[0] == '_') {
                 continue;
             }
             if ($v instanceof Shippo_Object) {
@@ -45,7 +45,7 @@ public static function convertShippoObjectToArray($values)
         }
         return $results;
     }
-    
+
     /**
      * Converts a response from the Shippo API to the corresponding PHP object.
      *