error.js

const UnimplementedError = createErrorType('Unimplemented');

const AuthError = createErrorType('AuthError');

const ResponseError = createErrorType('ResponseError', function(message, data) {
  this.data = data;
});

module.exports = {
  UnimplementedError,
  AuthError,
  ResponseError
};

function createErrorType(name, init) {
  function CustomError(message) {
    this.message = message;
    init && init.apply(this, arguments);
  }

  CustomError.prototype = Object.create(Error.prototype, {
    name: {
      value: name
    },
    constructor: {
      value: Error,
      enumerable: false,
      writable: true,
      configurable: true
    }
  });

  if (Object.setPrototypeOf) {
    Object.setPrototypeOf(CustomError, Error);
  } else {
    CustomError.__proto__ = Error;
  }

  return CustomError;
}