NULL breaks custom field entity_autocomplete default value

I’m trying to figure out how to leave an autocomplete field empty if there is no value. NULL didn’t work – which I think is normal. But using ‘ ‘ didn’t work either. How do I write my else statement below for when a field is empty?

A peek in the logs shows this error: Error: Call to a member function get() on null in …

So, I can see that it can’t be null… I’m just not sure what I am able to put there.
    
if (!empty($items[$delta]->description_term)) {
$default_term = DrupaltaxonomyEntityTerm::load($items[$delta]->description_term);
} else {
// can't be '' and can't be NULL?;
  $default_term = '';
  }
 
$element['description_term'] = array(
'#type' => 'entity_autocomplete',
'#target_type' => 'taxonomy_term',
'#selection_settings' => [
'target_bundles' => [
'descriptors'
],
],
'#title' => t('descriptor'),
'#field_prefix' => '',
'#prefix' => '<td>',
'#suffix' => '</td>',
'#size' => 18,
'#default_value' => $default_term,
'#required' => FALSE,
);

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/4/feed