title: devServer proxy in config throws 404
body: <p>I have this in <code>src/vue.config.js</code></p>
  
  <pre><code>module.exports = {
    devServer: {
      proxy: {
        '/api': {
          target: 'http://localhost:8081',
          changeOrigin: true,
        },
      },
    },
  };
  </code></pre>
  
  <p>and I'm calling the api with</p>
  
  <pre><code>  axios.get('/api/parts')
      .then(result =&gt; commit('updateParts', result.data))
      .catch(console.error);
  </code></pre>
  
  <p>But I just keep getting</p>
  
  <blockquote>
    <p>Error: "Request failed with status code 404"</p>
  </blockquote>
  
  <p>And I can see the request is being made to port 8080 instead of 8081</p>
  
  <p>I can access the api in the browser with no problems</p>
  
  <p>How can I debug this?</p>