Identifier "twig" is not defined - Silex Framework - php

Question

Thanks for you interest,
I have create this APP:
// web/index.php
require_once __DIR__.'/../vendor/autoload.php';
use Silex\Application;
use Silex\Provider\TwigServiceProvider;
$app = new Application();
$app['debug'] = true;
$app->register(new TwigServiceProvider(), array(
'twig.path' => __DIR__.'/templates',
'twig.class_path' => __DIR__.'/../vendor/twig/twig/lib',
'twig.options' => array('cache' => __DIR__.'/../cache'),
));
$app->get('/', function () use ($app) {
return $app['twig']->render('base.html.twig', array());
});
return $app;
But, when I load / in instance of base.html.twig be loaded, this error appear:
InvalidArgumentException: Identifier "twig" is not defined.
in /home/victor/workspace/testProject/vendor/pimple/pimple/lib/Pimple.php line 78
at Pimple->offsetGet('twig') in /home/victor/workspace/testProject/src/app.php line 41
at {closure}()
at call_user_func_array(object(Closure), array()) in /home/victor/workspace/testProject/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/HttpKernel.php line 145
at HttpKernel->handleRaw(object(Request), '1') in /home/victor/workspace/testProject/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/HttpKernel.php line 66
at HttpKernel->handle(object(Request), '1', true) in /home/victor/workspace/testProject/vendor/silex/silex/src/Silex/Application.php line 538
at Application->handle(object(Request)) in /home/victor/workspace/testProject/vendor/silex/silex/src/Silex/Application.php line 515
at Application->run() in /home/victor/workspace/testProject/web/index.php line 11
I have followed the official tutorial, installed it using composer and double checked all the paths...

Answer 1

Try removing the "twig.class_path" entry.
I have it like this, and it works:
$options = [
'twig.path' => ...,
'twig.options' => [
'strict_variables' => false
]
];
$this->_app->register(new TwigServiceProvider(), $options);