Placing a facet in the header of a view

I get an error when I place a facet in the header of a view

With facets 3.x it's possible to directly place a facet in the header of a view. When I do this, I get the following error:

The website encountered an unexpected error. Please try again later.
Error: Call to a member function getRegion() on null in uikit_theme_suggestions_block_alter() (line 46 of themes/contrib/uikit/includes/alter.inc).

uikit_theme_suggestions_block_alter(Array, Array, 'block') (Line: 449)
Drupal\Core\Theme\ThemeManager->alterForTheme(Object, 'theme_suggestions', Array, Array, 'block') (Line: 458)
Drupal\Core\Theme\ThemeManager->alter(Array, Array, Array, 'block') (Line: 245)
Drupal\Core\Theme\ThemeManager->render('block', Array) (Line: 433)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 446)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 479)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 42)
__TwigTemplate_05a24c5c758a81d80223b6b74b9797f0->doDisplay(Array, Array) (Line: 405)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 378)
Twig\Template->display(Array) (Line: 390)
Twig\Template->render(Array) (Line: 55)
twig_render_template('modules/contrib/facets/templates/facets-views-plugin.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('facets_views_plugin', Array) (Line: 433)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 446)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 479)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 71)
__TwigTemplate_72b41af1c608ae582d180ce54e8d525b->doDisplay(Array, Array) (Line: 405)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 378)
Twig\Template->display(Array) (Line: 390)
Twig\Template->render(Array) (Line: 55)
twig_render_template('themes/custom/adfcdduk/templates/views/views-view--suche.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('views_view__suche', Array) (Line: 433)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 446)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array, ) (Line: 242)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 580)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 243)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 132)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 142)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 174)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 81)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
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: 270)
Drupal\shield\ShieldMiddleware->bypass(Object, 1, 1) (Line: 137)
Drupal\shield\ShieldMiddleware->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 718)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)