title: TypeError: String cannot represent value: graphql Query not working
body: <p>I am trying to run a graphql Query but it keeps giving me the "TypeError: String cannot represent value:" error.</p>
  
  <p>The schema for my query:</p>
  
  <pre><code>    type User {
          active: Boolean!
          email: String!
          fullname: String!
          description: String!
          tags: [String!]!
      }
  
      type Query {
          getAllUsers: [User]!
      }
  </code></pre>
  
  <p>My resolver:</p>
  
  <pre><code>Query: {
          getAllUsers: (_, __, { dataSources }) =&gt; {
              return dataSources.userAPI.getAllUsers();
          }
      }
  </code></pre>
  
  <p>userAPI:</p>
  
  <pre class="lang-js prettyprint-override"><code>    getAllUsers() {
          const params = {
              TableName: 'Users',
              Select: 'ALL_ATTRIBUTES'
          };
  
          return new Promise((resolve, reject) =&gt; {
              dynamodb.scan(params, function(err, data) {
                  if (err) {
                      console.log('Error: ', err);
                      reject(err);
                  } else {
                      console.log('Success');
                      resolve(data.Items);
                  }
              });
          });
      }
  </code></pre>
  
  <p>The query:</p>
  
  <pre><code>query getAllUsers{
    getAllUsers{
      email
    }
  }
  </code></pre>
  
  <p>Since my email is a string, the error I'm getting is "String cannot represent value".</p>