Undefined variable: mimes

Hey,

I upgrade my CI installation from 2 to 3 and got the following php notice error when opening one of my existing controllers.

Message: Undefined variable: mimes
Filename: core/Output.php
Line Number: 107

PHP Code:

function __construct()
{
  $this->_zlib_oc = @ini_get('zlib.output_compression');

  // Get mime types for later
  if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'))
  {
    include APPPATH.'config/'.ENVIRONMENT.'/mimes.php';
  }
  else
  {
    include APPPATH.'config/mimes.php';
  }

  $this->mime_types = $mimes;

  log_message('debug', "Output Class Initialized");
} 


Could I change the following

PHP Code:

$this->mime_types = $mimes; 


to

PHP Code:

if (isset($mimes))
{
  $this->mime_types = $mimes;
} 


In order to resolve the problem ?