title: Undefined index with not array
body: <p>As long as I don't have debug on, this if statement works fine     </p>
  
  <pre><code>   if (!is_array($post_options['categoryid']['wpcatid'][1])) { 
         do something
    }
  </code></pre>
  
  <p>but with debug on I get this notice</p>
  
  <blockquote>
    <p>Notice: Undefined index: <code>wpcatid</code> </p>
  </blockquote>
  
  <p>question is now to define the index (I presume with isset), but will this work if it's set and empty (seems it's either set or empty)?</p>
  
  <p>Anyway, any advice on how to rid of this undefined index notice?</p>