When trying to add a book page to a book as a low privilege user the following TypeError occurs:
TypeError: Drupal\Component\Utility\NestedArray::getValue(): Argument #2 ($parents) must be of type array, null given, called in /app/drupal9/core/lib/Drupal/Core/Field/WidgetBase.php on line 426 in Drupal\Component\Utility\NestedArray::getValue() (line 69 of /app/drupal9/core/lib/Drupal/Component/Utility/NestedArray.php)
#0 /app/drupal9/core/lib/Drupal/Core/Field/WidgetBase.php(426): Drupal\Component\Utility\NestedArray::getValue(Array, NULL)
#1 /app/drupal9/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php(270): Drupal\Core\Field\WidgetBase->flagErrors(Object(Drupal\content_moderation\Plugin\Field\ModerationStateFieldItemList), Object(Symfony\Component\Validator\ConstraintViolationList), Array, Object(Drupal\Core\Form\FormState))
Steps to reproduce:
- Standard install of Drupal 9.5.11
- Install book module
- Install workflow module and content moderation module
- Edit the standard workflow and apply it to all content types
- Create a content editor user with the 'content editor' role
- Give the content editor role permission to 'create new drafts' as well as all book related permissions
- Log in as admin and create a new basic page, go to the book tab and select 'create new book' and save and publish it
- Log in as content editor and create a new basic page and save it (as 'draft')
- Log in as admin and publish the new basic page that was created by the content editor
- Log in as content editor and view the newly created page
- Click on the 'Outline' tab at the top of the page and add the new page to the book that was created earlier
- The TypeError above is thrown when you save the page