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