Remove unnecessary fallbacks when args accept null

Author: Seldaek

src/JsonSchema/Constraints/UndefinedConstraint.php

@@ -37,7 +37,7 @@ public function check(&$value, $schema = null, JsonPointer $path = null, $i = nu
             return;
         }
 
-        $path = $this->incrementPath($path ?: new JsonPointer(''), $i);
+        $path = $this->incrementPath($path, $i);
         if ($fromDefault) {
             $path->setFromDefault();
         }
@@ -140,7 +140,7 @@ protected function validateCommonProperties(&$value, $schema, JsonPointer $path,
                     if (!$this->getTypeCheck()->propertyExists($value, $required)) {
                         $this->addError(
                             ConstraintError::REQUIRED(),
-                            $this->incrementPath($path ?: new JsonPointer(''), $required), array(
+                            $this->incrementPath($path, $required), array(
                                 'property' => $required
                             )
                         );