Only dump object internals if a custom caster exists

src/Whoops/Handler/PrettyPageHandler.php

@@ -8,6 +8,8 @@ namespace Whoops\Handler;
 
 use InvalidArgumentException;
 use RuntimeException;
+use Symfony\Component\VarDumper\Cloner\AbstractCloner;
+use Symfony\Component\VarDumper\Cloner\VarCloner;
 use UnexpectedValueException;
 use Whoops\Exception\Formatter;
 use Whoops\Util\Misc;
@@ -117,6 +119,23 @@ class PrettyPageHandler extends Handler
         // @todo: Make this more dynamic
         $helper = new TemplateHelper();
 
+        $cloner = new VarCloner();
+        // Only dump object internals if a custom caster exists.
+        $cloner->addCasters(['*' => function ($obj, $a, $stub, $isNested, $filter = 0) {
+            $class = $stub->class;
+            $classes = [$class => $class] + class_parents($class) + class_implements($class);
+
+            foreach ($classes as $class) {
+                if (isset(AbstractCloner::$defaultCasters[$class])) {
+                    return $a;
+                }
+            }
+
+            // Remove all internals
+            return [];
+        }]);
+        $helper->setCloner($cloner);
+
         $templateFile = $this->getResource("views/layout.html.php");
         $cssFile      = $this->getResource("css/whoops.base.css");
         $zeptoFile    = $this->getResource("js/zepto.min.js");