title: Dynamically add errors when using useFieldArray with React Hook Form
body: <p>How would you go about dynamically adding custom error messages to inputs that are generated with useFieldArray?</p>
  <p>Very simple codesandbox here - <a href="https://codesandbox.io/s/romantic-dubinsky-xd6f7?file=/src/App.js" rel="nofollow noreferrer">https://codesandbox.io/s/romantic-dubinsky-xd6f7?file=/src/App.js</a></p>
  <p>Usually I would write something like <code>{errors.name &amp;&amp; &lt;p&gt;This can't be empty&lt;/p&gt;}</code> however with useFieldArray the names of the inputs are dynamically generated. I've tried something like <code>{errors.items.index.name &amp;&amp; &lt;p&gt;This can't be empty&lt;/p&gt;}</code> but that doesn't work.</p>
  <p>Any suggestions?</p>