diff --git a/lib/PicoTwigExtension.php b/lib/PicoTwigExtension.php
index e631736..d5490e7 100644
--- a/lib/PicoTwigExtension.php
+++ b/lib/PicoTwigExtension.php
@@ -93,13 +93,6 @@ class PicoTwigExtension extends Twig_Extension
      */
     public function markdownFilter($markdown)
     {
-        if ($this->getPico()->getParsedown() === null) {
-            throw new LogicException(
-                'Unable to apply Twig "markdown" filter: '
-                . 'Parsedown instance wasn\'t registered yet'
-            );
-        }
-
         return $this->getPico()->getParsedown()->text($markdown);
     }
 
diff --git a/plugins/DummyPlugin.php b/plugins/DummyPlugin.php
index 9214029..582d859 100644
--- a/plugins/DummyPlugin.php
+++ b/plugins/DummyPlugin.php
@@ -291,12 +291,12 @@ final class DummyPlugin extends AbstractPicoPlugin
      *
      * @see    Pico::getTwig()
      * @see    DummyPlugin::onPageRendered()
-     * @param  Twig_Environment &$twig          twig template engine
+     * @param  Twig_Environment $twig           twig template engine
      * @param  array            &$twigVariables template variables
      * @param  string           &$templateName  file name of the template
      * @return void
      */
-    public function onPageRendering(Twig_Environment &$twig, array &$twigVariables, &$templateName)
+    public function onPageRendering(Twig_Environment $twig, array &$twigVariables, &$templateName)
     {
         // your code
     }
diff --git a/themes/default/menu-icon.png b/themes/default/menu-icon.png
deleted file mode 100644
index 1cb463e..0000000
Binary files a/themes/default/menu-icon.png and /dev/null differ