title: How to make element 0 optional?
body: <p>Currently I have this:</p>
  
  <pre><code>type ArrayPlusRestCount&lt;T&gt; = [T &amp; {restCount: number} | undefined, ...T[]];
  </code></pre>
  
  <p>Any ideas how to make element 0 to not be required because currently something like:</p>
  
  <pre><code>const so: ArrayPlusRestCount&lt;number&gt; = [];
  </code></pre>
  
  <p>fails with:</p>
  
  <blockquote>
    <p>Property '0' is missing in type '[]' but required in type '[number &amp; { restCount: number; }, ...number[]]'</p>
  </blockquote>