Simple debug results in internal server error
Hi!! you can use a official symfony dumper, insert this line on the file "composer.json"  

"require-dev": {
    "symfony/var-dumper":"3.0.4"
  }


run the follow command:

composer install "symfony/var-dumper"


or

composer update


you can use in your code with these line:

dump($variable_name);


enjoy!!! ;)