Error message

Drupal\search_api_page\Controller\SearchApiPageController->page(Object, 'author', '')
call_user_func_array(Array, Array) (Line: 128)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 577)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 129)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 102)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
call_user_func_array(Object, Array) (Line: 139)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 62)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 62)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 53)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 211)
Drupal\page_cache\StackMiddleware\PageCache->fetch(Object, 1, 1) (Line: 125)
Drupal\page_cache\StackMiddleware\PageCache->lookup(Object, 1, 1) (Line: 79)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 55)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 644)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)