title: Vue + Apollo: TypeError: this.getClient(...).watchQuery is not a function
body: <p>I am trying to setup a very simple query using Vue + Apollo (Postgraphile GraphQL server in the backend).</p>
  
  <p>In my component I have (in the script tag):</p>
  
  <pre class="lang-js prettyprint-override"><code>import { CURRENT_USER_QUERY } from '../constants/graphql';
  
  export default {
    name: 'User',
    data() {
      return {
        currentUser: undefined,
      };
    },
    apollo: {
      currentUser: CURRENT_USER_QUERY,
    },
  };
  </code></pre>
  
  <p>In <code>../contants/graphql</code> I have:</p>
  
  <pre class="lang-js prettyprint-override"><code>import gql from 'graphql-tag';
  
  export const CURRENT_USER_QUERY = gql`
    query CurrentUserQuery {
      currentUser {
        id
        username
      }
    }
  `;
  </code></pre>
  
  <p>In my Graphiql endpoint, the query above works without any problems.</p>
  
  <p>However, when I run it in Vue, I get the following message on console:</p>
  
  <pre><code>[Vue warn]: Error in created hook: "TypeError: 
  this.getClient(...).watchQuery is not a function"
  </code></pre>
  
  <p>Searched everywhere and could not find anyone with a similar error...</p>
  
  <p>Any clues? Where should I start looking at?
  Thanks!!</p>