removed code that deal with potential null nodes (not possible anymore)

lib/Twig/Node.php

@@ -151,7 +151,7 @@ class Twig_Node implements Countable, IteratorAggregate
      */
     public function hasNode($name)
     {
-        return array_key_exists($name, $this->nodes);
+        return isset($this->nodes[$name]);
     }
 
     /**
@@ -163,7 +163,7 @@ class Twig_Node implements Countable, IteratorAggregate
      */
     public function getNode($name)
     {
-        if (!array_key_exists($name, $this->nodes)) {
+        if (!isset($this->nodes[$name])) {
             throw new LogicException(sprintf('Node "%s" does not exist for Node "%s".', $name, get_class($this)));
         }
 
@@ -176,7 +176,7 @@ class Twig_Node implements Countable, IteratorAggregate
      * @param string    $name
      * @param Twig_Node $node
      */
-    public function setNode($name, $node = null)
+    public function setNode($name, Twig_Node $node)
     {
         $this->nodes[$name] = $node;
     }
@@ -205,9 +205,7 @@ class Twig_Node implements Countable, IteratorAggregate
     {
         $this->filename = $filename;
         foreach ($this->nodes as $node) {
-            if (null !== $node) {
-                $node->setFilename($filename);
-            }
+            $node->setFilename($filename);
         }
     }
 

lib/Twig/NodeTraverser.php

@@ -70,10 +70,6 @@ class Twig_NodeTraverser
 
     private function traverseForVisitor(Twig_NodeVisitorInterface $visitor, Twig_Node $node = null)
     {
-        if (null === $node) {
-            return;
-        }
-
         $node = $visitor->enterNode($node, $this->env);
 
         foreach ($node as $k => $n) {

test/Twig/Tests/NodeVisitor/OptimizerTest.php

@@ -89,10 +89,6 @@ class Twig_Tests_NodeVisitor_OptimizerTest extends PHPUnit_Framework_TestCase
 
     public function checkForConfiguration(Twig_Node $node = null, $target, $withLoop)
     {
-        if (null === $node) {
-            return;
-        }
-
         foreach ($node as $n) {
             if ($n instanceof Twig_Node_For) {
                 if ($target === $n->getNode('value_target')->getAttribute('name')) {