title: Access of configuration variable in Cloud Functions Firebase CLI local emulator failed
body: <p>I am using Firebase Functions. I set a environment variable by command:</p>
  
  <pre><code>firebase functions:config:set my.token="abcde"
  </code></pre>
  
  <p>I verified it by command:</p>
  
  <pre><code>firebase functions:config:get
  </code></pre>
  
  <p>which returns me:</p>
  
  <pre><code>{
    "my": {
      "token": "abcde"
    }
  }
  </code></pre>
  
  <p>in my <strong>index.js</strong> , I try to get the set token by:</p>
  
  <pre><code>const tok = functions.config().my.token
  </code></pre>
  
  <p>I would like to test my functions locally instructed by <a href="https://firebase.google.com/docs/functions/local-emulator" rel="noreferrer">this document</a>, so I run command:</p>
  
  <pre><code>firebase serve --only functions
  </code></pre>
  
  <p>But it gives me error:</p>
  
  <pre><code>Error from emulator. FirebaseError: Error occurred while parsing your function triggers.
  TypeError: Cannot read property 'token' of undefined
  </code></pre>
  
  <p>Why I can't access the token I set in environment variable of Firebase?</p>