title: polkadot.js: Unable to create Enum
body: <p><code>types.json</code>:</p>
  <pre><code>{
    &quot;WorkerId&quot;: {
      &quot;_enum&quot;: {
        &quot;Single&quot;: &quot;Single&quot;,
        &quot;Double&quot;: &quot;Double&quot;
      }
    },
    &quot;Single&quot;: &quot;u8&quot;,
    &quot;Double&quot;: &quot;(u8, u8)&quot;,
  }
  </code></pre>
  <p>substrate code:</p>
  <pre class="lang-rust prettyprint-override"><code>#[pallet::storage]
  #[pallet::getter(fn worker_infos)]
  pub type WorkerInfos&lt;T: Config&gt; = StorageMap&lt;_, Twox64Concat, WorkerId, WorkerInfo, ValueQuery&gt;;
  
  
  pub enum WorkerId {
      Single(u8),
      Double(u8, u8),
  }
  </code></pre>
  <p>I want to query <code>worker_infos</code> by <code>WorkerId</code> in polkadot.js:</p>
  <pre class="lang-js prettyprint-override"><code>    workerIds = [1,2]
      api.query[wrpc][wcallable]
        .multi(workerIds, (results) =&gt; {
          ...
        })
        .then((unsub) =&gt; {
          ...
        })
        .catch(console.error);
  </code></pre>
  <p>Error info:</p>
  <pre><code>REGISTRY: Error: Unable to create Enum via index 2, in Single, Double
  </code></pre>
  <p>Any ideas on this? <strong>How to pass workerIds(enum type) in polkadot.js?</strong></p>