title: TypeScript query property does not exist
body: <p>I try to add Query types on GraphQL query using TypeScript, but i don't understand why TS return me this error : </p>
  
  <p><code>Property 'userMe' does not exist on type 'Query | null'.</code></p>
  
  <p>My Query : </p>
  
  <pre><code>const { userMe }: Query | null = cache.readQuery({
    query: ME,
  });
  </code></pre>
  
  <p>And my types :</p>
  
  <pre><code>export type Query = {
    __typename?: 'Query';
    files?: Maybe&lt;Array&lt;Maybe&lt;UploadFile&gt;&gt;&gt;;
    me?: Maybe&lt;UsersPermissionsMe&gt;;
    userMe?: Maybe&lt;CustomUsersPermissionsMe&gt;;
  };
  </code></pre>
  
  <p><code>userMe</code> is present, but not required. I don't understand why TS cry about this :D I use TS v3.7.5.</p>
  
  <p>Anyone can help me ?</p>