Fatal error when enabling Add to Calendar field on Drupal 11: TypeError: Cannot access offset of type Drupal\Core\StringTranslation\TranslatableMarkup

Issue information

From user: badeadrian

Related to !4 (merged)

Contribution record

Fork management

Description

When using the Add to Calendar Field Formatter module on Drupal 11, the site throws a fatal error when attempting to add the “Add to calendar” field to a content type.

Error message:

An AJAX HTTP error occurred.
HTTP Result Code: 500
StatusText: 500 Service unavailable (with message)

TypeError: Cannot access offset of type Drupal\Core\StringTranslation\TranslatableMarkup 
in Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition() 
(core/lib/Drupal/Component/Plugin/Discovery/DiscoveryTrait.php line 45)

Stack trace excerpt:

Drupal\Core\Plugin\DefaultPluginManager->getDefinition()
Drupal\field_ui\Controller\FieldStorageAddController->getFieldSelectionLinks()

This prevents the field from being added via the UI.

Root cause

In add_to_calendar.module, the base field definition uses a manually instantiated TranslatableMarkup object for the label:

$fields['add_to_calendar'] = BaseFieldDefinition::create('add_to_calendar')
  ->setLabel(new TranslatableMarkup('Add to calendar'))
  ->setComputed(TRUE)

Solution:
Replace new TranslatableMarkup() with the standard translation API call t():

$fields['add_to_calendar'] = BaseFieldDefinition::create('add_to_calendar')
  ->setLabel(t('Add to calendar'))
  ->setComputed(TRUE)
  ->setDisplayConfigurable('view', TRUE)
  ->setDisplayOptions('view', [
    'region' => 'hidden',
  ])
  ->setClass(AddToCalendarItemList::class);