title: Angular Abstract control remove error
body: <p>I want a way to remove a specific error from a form control and not clear all error.</p>
  
  <pre><code>control.setError({'firstError': true})
  </code></pre>
  
  <p>and to remove that specific error like</p>
  
  <pre><code>control.removeError({'firstError}) and not control.setError({null})
  </code></pre>
  
  <p>I tried </p>
  
  <pre><code>control.setError({'firstError': false})
  </code></pre>
  
  <p>but didn't work.</p>
  
  <p>Any help. Thanks</p>
  
  <p>angular 4.1.1</p>