title: useMutation always returns data undefined
body: <p>this my code   </p>
  
  <p><strong>React</strong></p>
  
  <pre><code>const EXCHANGE_RATES = gql`
    mutation {
      signUp(lastName: "Amasia")
    }
  `;
  const HandlerRequest = () =&gt; {
    const [loading, { data }] = useMutation(EXCHANGE_RATES);
  
    console.log('apollo', data);
  
    return &lt;p&gt;apollo&lt;/p&gt;;
  };
  </code></pre>
  
  <p><strong>Schema</strong></p>
  
  <pre><code>  gql`
    extend type Mutation {
      signUp(
        lastName: String!
      ): String!
    }
  `;
  </code></pre>
  
  <p><strong>Resolvers</strong></p>
  
  <pre><code>Mutation: {
      signUp: async (
        _,
        { lastName}
      ) =&gt; {
        try {
          console.log(lastName)
          return lastName;    
        } catch (error) {
          return 'error';
        }
      },
    },
  </code></pre>
  
  <p>useMutation always returns data undefined but at graphql playground are working.what am i doing netak ?.</p>