From 824b5e0b678669ca4144304d329e1cf9484175b5 Mon Sep 17 00:00:00 2001
From: Tom Yrjas <tom@creamarketing.fi>
Date: Mon, 29 Jun 2020 14:12:01 +0300
Subject: [PATCH 1/2] BUGFIX: Ensure $items isn't null in
 GridFieldDetailForm_ItemRequest->Breadcrumbs() prior to performing operations
 on it.

---
 .../GridFieldDetailForm_ItemRequest.php       | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php b/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
index 9aab66baf..2a0a0a7ea 100644
--- a/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
+++ b/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
@@ -786,17 +786,19 @@ class GridFieldDetailForm_ItemRequest extends RequestHandler
         /** @var ArrayList $items */
         $items = $this->popupController->Breadcrumbs($unlinked);
 
-        if ($this->record && $this->record->ID) {
-            $title = ($this->record->Title) ? $this->record->Title : "#{$this->record->ID}";
-            $items->push(new ArrayData([
-                'Title' => $title,
-                'Link' => $this->Link()
-            ]));
-        } else {
-            $items->push(new ArrayData([
-                'Title' => _t('SilverStripe\\Forms\\GridField\\GridField.NewRecord', 'New {type}', ['type' => $this->record->i18n_singular_name()]),
-                'Link' => false
-            ]));
+        if ($items) {
+            if ($this->record && $this->record->ID) {
+                $title = ($this->record->Title) ? $this->record->Title : "#{$this->record->ID}";
+                $items->push(new ArrayData([
+                    'Title' => $title,
+                    'Link' => $this->Link()
+                ]));
+            } else {
+                $items->push(new ArrayData([
+                    'Title' => _t('SilverStripe\\Forms\\GridField\\GridField.NewRecord', 'New {type}', ['type' => $this->record->i18n_singular_name()]),
+                    'Link' => false
+                ]));
+            }
         }
 
         $this->extend('updateBreadcrumbs', $items);

From 00ee8d8abf4ca0535eee55bb722ccc9ea41e9fec Mon Sep 17 00:00:00 2001
From: Tom Yrjas <tom@creamarketing.fi>
Date: Mon, 29 Jun 2020 16:07:24 +0300
Subject: [PATCH 2/2] BUGFIX: Re-declare $items to be an ArrayList if it's null
 	getBackLink() modified to tolerate empty ArrayList

---
 .../GridFieldDetailForm_ItemRequest.php       | 34 +++++++++++--------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php b/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
index 2a0a0a7ea..9db76aac0 100644
--- a/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
+++ b/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
@@ -464,8 +464,10 @@ class GridFieldDetailForm_ItemRequest extends RequestHandler
             if ($toplevelController->hasMethod('Backlink')) {
                 $backlink = $toplevelController->Backlink();
             } elseif ($this->popupController->hasMethod('Breadcrumbs')) {
-                $parents = $this->popupController->Breadcrumbs(false)->items;
-                $backlink = array_pop($parents)->Link;
+                $parents = $this->popupController->Breadcrumbs(false);
+                if ($parents && $parents = $parents->items) {
+                    $backlink = array_pop($parents)->Link;
+                }
             }
         }
         if (!$backlink) {
@@ -786,19 +788,21 @@ class GridFieldDetailForm_ItemRequest extends RequestHandler
         /** @var ArrayList $items */
         $items = $this->popupController->Breadcrumbs($unlinked);
 
-        if ($items) {
-            if ($this->record && $this->record->ID) {
-                $title = ($this->record->Title) ? $this->record->Title : "#{$this->record->ID}";
-                $items->push(new ArrayData([
-                    'Title' => $title,
-                    'Link' => $this->Link()
-                ]));
-            } else {
-                $items->push(new ArrayData([
-                    'Title' => _t('SilverStripe\\Forms\\GridField\\GridField.NewRecord', 'New {type}', ['type' => $this->record->i18n_singular_name()]),
-                    'Link' => false
-                ]));
-            }
+        if (!$items) {
+            $items = new ArrayList();
+        }
+
+        if ($this->record && $this->record->ID) {
+            $title = ($this->record->Title) ? $this->record->Title : "#{$this->record->ID}";
+            $items->push(new ArrayData([
+                'Title' => $title,
+                'Link' => $this->Link()
+            ]));
+        } else {
+            $items->push(new ArrayData([
+                'Title' => _t('SilverStripe\\Forms\\GridField\\GridField.NewRecord', 'New {type}', ['type' => $this->record->i18n_singular_name()]),
+                'Link' => false
+            ]));
         }
 
         $this->extend('updateBreadcrumbs', $items);