Replace Drupal's error handling with Symfony/HttpKernel's

Problem

• WSOD. No error. Nothing.

Cause

Symfony\Component\HttpKernel\Kernel.php:

    public function init()
    {
        if ($this->debug) {
            ini_set('display_errors', 1);
            error_reporting(-1);

            DebugClassLoader::enable();
            ErrorHandler::register($this->errorReportingLevel);
            if ('cli' !== php_sapi_name()) {
                ExceptionHandler::register();
            }
        } else {
            ini_set('display_errors', 0);
        }
    }

Details

• index.php calls
  

  $kernel = new DrupalKernel('prod', FALSE);
  

• The second argument is $debug, tacked onto $this->debug by the Kernel's constructor.
• The rest is visible in the pasted snippet above.