Problem/Motivation
I have a Drupal 9.3 site with php 7.3. After enabling the render-example module I try to go to the link "Demonstration of render array usage." and I receive an error "502 Proxy Error", in the log messages I have many warnings with the following content:
Warning: var_export does not handle circular references en Drupal\Component\Utility\Variable::export() (línea 88 de /var/www/html/my-site/web/core/lib/Drupal/Component/Utility/Variable.php)
#0 /var/www/html/my-site/web/core/includes/bootstrap.inc(346): _drupal_error_handler_real(2, 'var_export does...', '/var/www/html/m...', 88)
#1 [internal function]: _drupal_error_handler(2, 'var_export does...', '/var/www/html/m...', 88, Array)
#2 /var/www/html/my-site/web/core/lib/Drupal/Component/Utility/Variable.php(88): var_export(Object(Drupal\Core\StringTranslation\TranslatableMarkup), true)
#3 /var/www/html/my-site/web/core/lib/Drupal/Component/Utility/Variable.php(60): Drupal\Component\Utility\Variable::export(Object(Drupal\Core\StringTranslation\TranslatableMarkup), ' ', false)
#4 /var/www/html/my-site/web/modules/contrib/examples/modules/render_example/src/Controller/RenderExampleController.php(407): Drupal\Component\Utility\Variable::export(Array)
#5 [internal function]: Drupal\render_example\Controller\RenderExampleController->arrays()
#6 /var/www/html/my-site/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#7 /var/www/html/my-site/web/core/lib/Drupal/Core/Render/Renderer.php(564): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#8 /var/www/html/my-site/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#9 /var/www/html/my-site/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#10 /var/www/html/my-site/vendor/symfony/http-kernel/HttpKernel.php(158): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#11 /var/www/html/my-site/vendor/symfony/http-kernel/HttpKernel.php(80): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#12 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/Session.php(58): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#13 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#14 /var/www/html/my-site/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#15 /var/www/html/my-site/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#16 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#17 /var/www/html/my-site/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#18 /var/www/html/my-site/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#19 /var/www/html/my-site/web/core/lib/Drupal/Core/DrupalKernel.php(708): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#20 /var/www/html/my-site/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#21 {main}
Steps to reproduce
Proposed resolution
Remaining tasks
User interface changes
API changes
Data model changes