class ValidationError extends Error {
  constructor(message, code) {
    super(message);
    this.name = 'ValidationError';
    this.code = code;
  }
}

function processData(data) {
  try {
    if (!data) throw new ValidationError('Data required', 'MISSING_DATA');
    return data.toUpperCase();
  } catch (error) {
    if (error instanceof ValidationError) {
      console.log(`${error.name}: ${error.message} (${error.code})`);
    } else {
      console.log(`Unexpected error: ${error.message}`);
    }
  }
}

processData(null);
processData(42);