From 17ff327271611fc6a315f8afd3e63d96ed40ba03 Mon Sep 17 00:00:00 2001
From: Aaron McGowan <me@amcgowan.ca>
Date: Thu, 1 Jun 2017 05:01:56 -0400
Subject: [PATCH] Bugfix: Resolves PHP notices when the prefix element is
 undefined.

---
 .../Field/FieldWidget/EntityReferenceBrowserWidget.php      | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/modules/lightning_features/lightning_media/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php b/modules/lightning_features/lightning_media/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php
index 3efb8b27e..62da83570 100644
--- a/modules/lightning_features/lightning_media/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php
+++ b/modules/lightning_features/lightning_media/src/Plugin/Field/FieldWidget/EntityReferenceBrowserWidget.php
@@ -18,8 +18,10 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
     $element = parent::formElement($items, $delta, $element, $form, $form_state);
 
     // Move the remaining number of selections to the details summary.
-    $element['#description'] .= $element['current']['#prefix'];
-    unset($element['current']['#prefix']);
+    if (isset($element['current']['#prefix'])) {
+      $element['#description'] .= $element['current']['#prefix'];
+      unset($element['current']['#prefix']);
+    }
 
     // Wrap the current selections in a nice <details> element.
     $cardinality = $this->fieldDefinition