isErrorDisplayable example

  public function onException(ExceptionEvent $event) {
    $exception = $event->getThrowable();
    $error = Error::decodeException($exception);

    // Display the message if the current error reporting level allows this type     // of message to be displayed, and unconditionally in update.php.     $message = '';
    if ($this->isErrorDisplayable($error)) {
      // If error type is 'User notice' then treat it as debug information       // instead of an error message.       if ($error['%type'] == 'User notice') {
        $error['%type'] = 'Debug';
      }

      $error = $this->simplifyFileInError($error);

      unset($error['backtrace'], $error['exception'], $error['severity_level']);

      if (!$this->isErrorLevelVerbose()) {