error

• Deprecated function: trim(): Passing null to parameter #1 ($string) of type string is deprecated in Drupal\robotstxt\Controller\RobotsTxtController->content() (line 71 of modules/contrib/robotstxt/src/Controller/RobotsTxtController.php).

  Drupal\robotstxt\Controller\RobotsTxtController->content()
  call_user_func_array() (Line: 123)
  Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 627)
  Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 121)
  Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
  Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 183)
  Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
  Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 54)
  Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle() (Line: 53)
  Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
  Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
  Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 201)
  Drupal\page_cache\StackMiddleware\PageCache->fetch() (Line: 138)
  Drupal\page_cache\StackMiddleware\PageCache->lookup() (Line: 87)
  Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
  Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
  Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 53)
  Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 38)
  Drupal\mercury_editor\StackMiddleware\AjaxPageState->handle() (Line: 51)
  Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 715)
  Drupal\Core\DrupalKernel->handle() (Line: 19)