diff --git a/core/lib/Drupal/Core/Entity/EntityFormController.php b/core/lib/Drupal/Core/Entity/EntityFormController.php
index 6a4b498..e4acf56 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormController.php
@@ -189,11 +189,12 @@ public function processForm($element, $form_state, $form) {
     // Hide or assign weights for extra fields.
     $extra_fields = field_info_extra_fields($this->entity->entityType(), $this->entity->bundle(), 'form');
     foreach ($extra_fields as $extra_field => $info) {
-      if (!$this->getFormDisplay($form_state)->getComponent($extra_field)) {
+      $component = $this->getFormDisplay($form_state)->getComponent($extra_field);
+      if (!$component) {
         $element[$extra_field]['#access'] = FALSE;
       }
-      elseif (!isset($element[$extra_field]['#weight'])) {
-        $element[$extra_field]['#weight'] = $info['weight'];
+      else {
+        $element[$extra_field]['#weight'] = $component['weight'];
       }
     }
 
diff --git a/core/modules/field/lib/Drupal/field/FieldInfo.php b/core/modules/field/lib/Drupal/field/FieldInfo.php
index 23ad2c4..f791af8 100644
--- a/core/modules/field/lib/Drupal/field/FieldInfo.php
+++ b/core/modules/field/lib/Drupal/field/FieldInfo.php
@@ -543,7 +543,7 @@ public function getBundleExtraFields($entity_type, $bundle) {
     drupal_alter('field_extra_fields', $extra);
 
     if (isset($extra[$entity_type][$bundle])) {
-      $info = $extra[$entity_type][$bundle] + $info;
+      $info += $extra[$entity_type][$bundle];
     }
 
     // Store in the 'static' and persistent caches.