eleminate a warning and add another hook form alter

disable_field_autocomplete.module

@@ -30,6 +30,13 @@ function disable_field_autocomplete_form_node_islandora_object_edit_form_alter(&
   $form['#validate'][] = 'disable_field_autocomplete_node_edit_validate';
 }
 
+/**
+ * Implements hook_form_alter().
+ */
+function disable_field_autocomplete_form_node_islandora_object_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
+  $form['#validate'][] = 'disable_field_autocomplete_node_edit_validate';
+}
+
 
 /**
  * Extra Islandora Ojbect node validation required due to lacking autocomplete.
@@ -54,6 +61,9 @@ function disable_field_autocomplete_node_edit_validate(&$form, \Drupal\Core\Form
 function disable_field_autocomplete_validate_fields($field_id, $form, \Drupal\Core\Form\FormStateInterface $form_state) {
   $contributor_count = 0;
   $contributors = &$form_state->getValue($field_id);
+  if(empty($contributors)) {
+    return;
+  }
   foreach ($contributors as &$contributor) {
     if (is_array($contributor) && isset($contributor['target_id']) && is_array($contributor['target_id'])) {
       $entity = ($contributor['target_id']['entity']);
@@ -65,7 +75,7 @@ function disable_field_autocomplete_validate_fields($field_id, $form, \Drupal\Co
             $contributor['target_id'] = $term_id;
           }
         } catch (Exception $e) {
-          $form_state->setError($form['field_linked_agent']['widget'][$contributor_count],
+          $form_state->setError($form[$field_id]['widget'][$contributor_count],
             t('The entered Term %name is not unique across Vocabularies.  You will need to include
       the term id in brackets.  For Example "%name (119)", where 119 is the term id.', array('%name' => $name)));
         }