The following error occurs when clicking on Processors tab in Search API index settings:
Error: Call to a member function getBackend() on null in Drupal\elasticsearch_connector\Plugin\search_api\processor\ExcludeSourceFields::supportsIndex() (line 64 of modules/contrib/elasticsearch_connector/src/Plugin/search_api/processor/ExcludeSourceFields.php).
Drupal\elasticsearch_connector\Plugin\search_api\processor\ExcludeSourceFields::supportsIndex(Object)
call_user_func(Array, Object) (Line: 371)
Drupal\search_api\Form\IndexProcessorsForm->getAllProcessors() (Line: 103)
Drupal\search_api\Form\IndexProcessorsForm->form(Array, Object) (Line: 117)
Drupal\Core\Entity\EntityForm->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 519)
Drupal\Core\Form\FormBuilder->retrieveForm('search_api_index_processors_form', Object) (Line: 276)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 93)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 151)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)