BEF php 8.1.2 / TypeError: count(): Argument #1 ($value) must be of type Countable|array, null given

Problem/Motivation

The website encountered an unexpected error. Please try again later.
TypeError: count(): Argument #1 ($value) must be of type Countable|array, null given in count() (line 62 of core/lib/Drupal/Core/Render/Element/Radios.php).

count() (Line: 62)
Drupal\Core\Render\Element\Radios::processRadios()
call_user_func_array() (Line: 1007)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 1070)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 574)
Drupal\Core\Form\FormBuilder->processForm() (Line: 320)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 134)
Drupal\views\Plugin\views\exposed_form\ExposedFormPluginBase->renderExposedForm() (Line: 1238)
Drupal\views\ViewExecutable->build() (Line: 70)
views_fieldsets_views_ui_display_tab_alter() (Line: 562)
Drupal\Core\Extension\ModuleHandler->alter() (Line: 381)
Drupal\views_ui\ViewEditForm->getDisplayTab() (Line: 204)
Drupal\views_ui\ViewEditForm->form() (Line: 106)
Drupal\Core\Entity\EntityForm->buildForm() (Line: 41)
Drupal\views_ui\ViewFormBase->buildForm()
call_user_func_array() (Line: 531)
Drupal\Core\Form\FormBuilder->retrieveForm() (Line: 278)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 48)
Drupal\Core\Entity\EntityFormBuilder->getForm() (Line: 230)
Drupal\views_ui\Controller\ViewsUIController->edit()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 564)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 158)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 80)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 58)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 23)
Stack\StackedHttpKernel->handle() (Line: 709)
Drupal\Core\DrupalKernel->handle() (Line: 19)

Steps to reproduce

1. Add an exposed entity reference filter (e.g., Taxonomy term field)
2. Leave "Autocomplete" as the "Selection type" in the filter settings
3. Enable BEF on view
4. Set BEF settings for filter to use checkbox/radios

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes