title: Gatsby.js - proxy to express server
body: <p>I want to setup proxy for my simple express server. I have added cors policy and everything works perfect when I call api like this:</p>
  
  <pre><code>fetch('http://localhost:3000/tasks')
  </code></pre>
  
  <p>But when i setup proxy in gatsby.config.js like this: </p>
  
  <pre><code>proxy: {
      prefix: '/',
      url: 'http://localhost:3000'
    },
  </code></pre>
  
  <p>and call:</p>
  
  <pre><code>fetch('/tasks)
  </code></pre>
  
  <p>I'm getting this error:</p>
  
  <blockquote>
    <p>Unhandled Rejection (SyntaxError): Unexpected token &lt; in JSON at position 0</p>
  </blockquote>
  
  <p>How to setup properly proxy in gatsby.js ??</p>