fixed some issues

src/Error/LoaderError.php

@@ -31,7 +31,7 @@ class LoaderError extends Error
         \Exception::__construct('', 0, $previous);
 
         $this->appendMessage($message);
-        $this->setTemplateLine(false);
+        $this->setTemplateLine(-2);
     }
 }
 

src/Node/Expression/CallExpression.php

@@ -277,7 +277,7 @@ abstract class CallExpression extends AbstractExpression
                 return [null, []];
             }
             $r = new \ReflectionMethod($callable[0], $callable[1]);
-        } elseif (\is_object($callable) && !$callable instanceof Closure) {
+        } elseif (\is_object($callable) && !$callable instanceof \Closure) {
             $r = new \ReflectionObject($callable);
             $r = $r->getMethod('__invoke');
             $callable = [$callable, '__invoke'];

src/Template.php

@@ -226,7 +226,7 @@ abstract class Template implements \Twig_TemplateInterface
 
                 // this is mostly useful for \Twig\Error\LoaderError exceptions
                 // see \Twig\Error\LoaderError
-                if (false === $e->getTemplateLine()) {
+                if (-2 === $e->getTemplateLine()) {
                     $e->setTemplateLine(-1);
                     $e->guess();
                 }
@@ -371,7 +371,7 @@ abstract class Template implements \Twig_TemplateInterface
                 $e->setSourceContext($templateName ? new Source('', $templateName) : $this->getSourceContext());
             }
 
-            if ($e->getTemplateLine()) {
+            if ($e->getTemplateLine() > 0) {
                 throw $e;
             }
 
@@ -439,7 +439,7 @@ abstract class Template implements \Twig_TemplateInterface
 
             // this is mostly useful for \Twig\Error\LoaderError exceptions
             // see \Twig\Error\LoaderError
-            if (false === $e->getTemplateLine()) {
+            if (-2 === $e->getTemplateLine()) {
                 $e->setTemplateLine(-1);
                 $e->guess();
             }

src/Util/TemplateDirIterator.php

@@ -14,7 +14,7 @@ namespace Twig\Util;
 /**
  * @author Fabien Potencier <fabien@symfony.com>
  */
-class TemplateDirIterator extends IteratorIterator
+class TemplateDirIterator extends \IteratorIterator
 {
     public function current()
     {