Is there a way to check if the value of a field within the preprocess is empty? I'm getting an Error: Call to a member function isEmpty() error during the process

function iom_preprocess_block__twitterfeed(&$variables) {
 
    // Get the twitter_username field from node
    $twitterUsername = \Drupal::routeMatch()
                        ->getParameter('node')
                        ->get('field_twitter_username')
                        ->value; 

     if ($twitterUsername->isEmpty()) {
         dump("Empty");
     }
 
     else {
         dump("Not Empty");
     }
 
}

Is there a way to check, in a preprocess function, if the value of a field is empty? 

I'm getting the following error.

Call to a member function isEmpty()

function iom_preprocess_block__twitterfeed(&$variables) {
  // Get the twitter_username field from node.
  $twitterUsername = \Drupal::routeMatch()
    ->getParameter('node')
    ->get('field_twitter_username')
    ->value; 

  if ($twitterUsername->isEmpty()) {
    dump("Empty");
  }
  else {
    dump("Not Empty");
  }
}