"entities" is an invalid render array key

After the batch search finished, very often the following errors are displayed:

User error: "entities" is an invalid render array key in Drupal\Core\Render\Element::children() (line 97 of core/lib/Drupal/Core/Render/Element.php).
Drupal\Core\Render\Element::children(Array, 1) (Line: 402)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
Drupal\Core\Render\Renderer->render(Array) (Line: 501)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 59)
__TwigTemplate_c09fe2afd76a6e78c834085bce1fd20e6a7e2dc33bc43bd8bfe7dd534e7495c9->doDisplay(Array, Array) (Line: 455)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 422)
Twig\Template->display(Array) (Line: 434)
Twig\Template->render(Array) (Line: 64)
twig_render_template('modules/contrib/scanner/templates/scanner-results.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('scanner_results', Array) (Line: 431)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
Drupal\Core\Render\Renderer->render(Array) (Line: 164)
Drupal\scanner\Form\ScannerForm->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 532)
Drupal\Core\Form\FormBuilder->retrieveForm('scanner_form', Object) (Line: 371)
Drupal\Core\Form\FormBuilder->rebuildForm('scanner_form', Object) (Line: 254)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 91)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 573)
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: 708)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)
User error: "matches" is an invalid render array key in Drupal\Core\Render\Element::children() (line 97 of core/lib/Drupal/Core/Render/Element.php).
Drupal\Core\Render\Element::children(Array, 1) (Line: 402)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
Drupal\Core\Render\Renderer->render(Array) (Line: 501)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 59)
__TwigTemplate_c09fe2afd76a6e78c834085bce1fd20e6a7e2dc33bc43bd8bfe7dd534e7495c9->doDisplay(Array, Array) (Line: 455)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 422)
Twig\Template->display(Array) (Line: 434)
Twig\Template->render(Array) (Line: 64)
twig_render_template('modules/contrib/scanner/templates/scanner-results.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('scanner_results', Array) (Line: 431)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 200)
Drupal\Core\Render\Renderer->render(Array) (Line: 164)
Drupal\scanner\Form\ScannerForm->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 532)
Drupal\Core\Form\FormBuilder->retrieveForm('scanner_form', Object) (Line: 371)
Drupal\Core\Form\FormBuilder->rebuildForm('scanner_form', Object) (Line: 254)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 91)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 573)
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: 708)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

The actually results are still shown on the page however. I haven't found a pattern as to why it happens most, but not all of the time. This is searching just a basic page body field.