Merge pull request #70 from leganz/master

If user (access_token pair) has insufficient rights, it will result in "Undefined property: stdClass::$errors"

Author: christophrumpel

src/Exceptions/CouldNotSendNotification.php

@@ -10,6 +10,10 @@ class CouldNotSendNotification extends \Exception
      */
     public static function serviceRespondsNotSuccessful($response)
     {
+        if (isset($response->error)){
+            return new static("Couldn't post notification. Response: ".$response->error);
+        }
+
         $responseBody = print_r($response->errors[0]->message, true);
 
         return new static("Couldn't post notification. Response: ".$responseBody);