Fix lookForErrors Issue with 2.0.0

[fastdivision]

Fixes #167

PHP Fatal error:  Uncaught Error: Cannot use object of type stdClass as array in /vendor/automattic/woocommerce/src/WooCommerce/HttpClient/HttpClient.php:341

Stack trace:
#0 /vendor/automattic/woocommerce/src/WooCommerce/HttpClient/HttpClient.php(378): Automattic\WooCommerce\HttpClient\HttpClient->lookForErrors(Object(stdClass))
#1 /vendor/automattic/woocommerce/src/WooCommerce/HttpClient/HttpClient.php(414): Automattic\WooCommerce\HttpClient\HttpClient->processResponse()
#2 /vendor/automattic/woocommerce/src/WooCommerce/Client.php(82): Automattic\WooCommerce\HttpClient\HttpClient->request('orders', 'GET', Array, Array)

Example object:

array(1) {
  [0]=>
  object(stdClass)#44 (2) {
    ["code"]=>
    string(36) "woocommerce_api_authentication_error"
    ["message"]=>
    string(19) "API user is invalid"
  }
}

[CheatCodes]

Any plans tagging a new release including this fix?