Deleting a collection with children causes error with islandora_breadcrumbs module

[ainsofs]

Steps to re-create:

1. Install default Islandora from Ansible
2. Create a collection
3. Add children
4. Delete collection
5. View child object

Work-around

Disabling islandora_breadcrumbs module or commenting out line 111 (as below) makes it work

/var/www/html/drupal/web/modules/contrib/islandora/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php

108    // Find the next in the chain, if there are any.
109    if ($entity->hasField($this->config->get('referenceField')) &&
110      !$entity->get($this->config->get('referenceField'))->isEmpty()) {
111      // $this->walkMembership($entity->get($this->config->get('referenceField'))->entity, $crumbs);
112    }

Error

The website encountered an unexpected error. Please try again later.
TypeError: Argument 1 passed to Drupal\islandora_breadcrumbs\IslandoraBreadcrumbBuilder::walkMembership() must implement interface Drupal\Core\Entity\EntityInterface, null given, called in /var/www/html/drupal/web/modules/contrib/islandora/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php on line 111 in Drupal\islandora_breadcrumbs\IslandoraBreadcrumbBuilder->walkMembership() (line 93 of modules/contrib/islandora/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php).
Drupal\islandora_breadcrumbs\IslandoraBreadcrumbBuilder->walkMembership(NULL, Array) (Line: 111)
Drupal\islandora_breadcrumbs\IslandoraBreadcrumbBuilder->walkMembership(Object, Array) (Line: 72)
Drupal\islandora_breadcrumbs\IslandoraBreadcrumbBuilder->build(Object) (Line: 83)
Drupal\Core\Breadcrumb\BreadcrumbManager->build(Object) (Line: 72)
Drupal\system\Plugin\Block\SystemBreadcrumbBlock->build() (Line: 171)
Drupal\block\BlockViewBuilder::preRender(Array)

[ainsofs]

Patch

Not tested but below seems to get rid of the error

diff --git a/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php b/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php
index c58e700..86090ff 100644
--- a/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php
+++ b/modules/islandora_breadcrumbs/src/IslandoraBreadcrumbBuilder.php
@@ -107,7 +107,8 @@ class IslandoraBreadcrumbBuilder implements BreadcrumbBuilderInterface {
 
     // Find the next in the chain, if there are any.
     if ($entity->hasField($this->config->get('referenceField')) &&
-      !$entity->get($this->config->get('referenceField'))->isEmpty()) {
+      !$entity->get($this->config->get('referenceField'))->isEmpty() &&
+      $entity->get($this->config->get('referenceField'))->entity instanceof EntityInterface) {
       $this->walkMembership($entity->get($this->config->get('referenceField'))->entity, $crumbs);
     }
   }

[dannylamb]

Resolved via Islandora/islandora@bfab343