protected function listValidationErrors(array $errors, OutputInterface $output)
    {
        if (count($errors) === 1) {
            $this->stdErr->writeln('The following error was found:');
        } else {
            $this->stdErr->writeln(sprintf(
                'The following %d errors were found:',
                count($errors)
            ));
        }

        foreach ($errors as $key => $error) {
            if (is_string($key) && strlen($key)) {
                $output->writeln("$key: $error");
            } else {
                $output->writeln($error);
            }
        }
    }