Issue #1927884 by Alan D., swentel: Always return an array from field_get_items().

core/modules/field/field.module

@@ -991,12 +991,12 @@ function field_view_field(EntityInterface $entity, $field_name, $display_options
  *   Defaults to the current language.
  *
  * @return
- *   An array of field items keyed by delta if available, FALSE otherwise.
+ *   An array with available field items keyed by delta.
  */
 function field_get_items(EntityInterface $entity, $field_name, $langcode = NULL) {
   $entity = $entity->getBCEntity();
   $langcode = field_language($entity, $field_name, $langcode);
-  return isset($entity->{$field_name}[$langcode]) ? $entity->{$field_name}[$langcode] : FALSE;
+  return isset($entity->{$field_name}[$langcode]) ? $entity->{$field_name}[$langcode] : array();
 }
 
 /**

core/modules/taxonomy/lib/Drupal/taxonomy/Plugin/views/argument_default/Tid.php

@@ -139,11 +139,8 @@ function get_argument() {
         foreach ($fields as $name => $info) {
           $field_info = field_info_field($name);
           if ($field_info['type'] == 'taxonomy_term_reference') {
-            $items = field_get_items($node, $name);
-            if (is_array($items)) {
-              foreach ($items as $item) {
-                $taxonomy[$item['tid']] = $field_info['settings']['allowed_values'][0]['vocabulary'];
-              }
+            foreach (field_get_items($node, $name) as $item) {
+              $taxonomy[$item['tid']] = $field_info['settings']['allowed_values'][0]['vocabulary'];
             }
           }
         }