errors.js

'use strict'

function createError (type, Proto) {
  const Err = function (message, cause) {
    if (typeof message === 'object' && message !== null) {
      // Can be passed just a cause
      cause = cause || message
      message = message.message || message.name
    }

    message = message || ''
    cause = cause || undefined

    // If input is already of type, return as-is to keep its stack trace.
    // Avoid instanceof, for when node_modules has multiple copies of level-errors.
    if (typeof cause === 'object' && cause.type === type && cause.message === message) {
      return cause
    }

    Object.defineProperty(this, 'type', { value: type, enumerable: false, writable: true, configurable: true })
    Object.defineProperty(this, 'name', { value: type, enumerable: false, writable: true, configurable: true })
    Object.defineProperty(this, 'cause', { value: cause, enumerable: false, writable: true, configurable: true })
    Object.defineProperty(this, 'message', { value: message, enumerable: false, writable: true, configurable: true })

    Error.call(this)

    if (typeof Error.captureStackTrace === 'function') {
      Error.captureStackTrace(this, Err)
    }
  }

  Err.prototype = new Proto()
  return Err
}

const LevelUPError = createError('LevelUPError', Error)

module.exports = {
  LevelUPError: LevelUPError,
  InitializationError: createError('InitializationError', LevelUPError),
  OpenError: createError('OpenError', LevelUPError),
  ReadError: createError('ReadError', LevelUPError),
  WriteError: createError('WriteError', LevelUPError),
  NotFoundError: createError('NotFoundError', LevelUPError),
  EncodingError: createError('EncodingError', LevelUPError)
}

module.exports.NotFoundError.prototype.notFound = true
module.exports.NotFoundError.prototype.status = 404