errors.js

// TypedError class which other typed errors subclass from.
class TypedError extends Error {

  constructor (message) {
    super();

    if (Error.hasOwnProperty('captureStackTrace'))
      Error.captureStackTrace(this, this.constructor);
    else
      Object.defineProperty(this, 'stack', {
        value: (new Error()).stack
      });

    Object.defineProperty(this, 'message', {
      value: message
    });
  }

  get name () {
    return this.constructor.name;
  }

}

export class NotFoundError extends TypedError {}
export class MethodError extends TypedError {}
export class NotAcceptableError extends TypedError {}
export class UnsupportedError extends TypedError {}