You should definitely check the presence of app_key and app_id before using them, ie:

```coffeescript
unless app_id? and app_key?
   msg.reply "Missing HUBOT_YUMMLY_APP_ID and HUBOT_YUMMLY_APP_KEY, so can't help sate your hunger :sweat: Go to https://developer.yummly.com/signup get started, and set those variables in your environment to help me help you
  return
```