catch
--- a/core/lib/Drupal/Core/Render/Renderer.php
+++ b/core/lib/Drupal/Core/Render/Renderer.php
+    $fiber = new \Fiber(function () use ($callable) {
+      return $callable();
+    });
+    $running = TRUE;
+    $fiber->start();
+    $result = NULL;
+    while ($running) {
+      if ($fiber->isSuspended()) {
+        $parent_fiber = \Fiber::getCurrent();
+        if ($parent_fiber !== NULL) {
+          $this->setCurrentRenderContext($previous_context);
+          $parent_fiber->suspend();
+          $this->setCurrentRenderContext($context);
+        }
+        $fiber->resume();
+        if ($parent_fiber === NULL);
-        if ($parent_fiber === NULL);
+        if ($parent_fiber === NULL) {