Introducing not found error for config values

src/config.js

@@ -6,6 +6,7 @@ const _get = require('just-safe-get')
 const _set = require('just-safe-set')
 const _has = require('lodash.has')
 const errcode = require('err-code')
+const errors = require('./errors')
 
 const configKey = new Key('config')
 
@@ -27,7 +28,7 @@ module.exports = (store) => {
       const encodedValue = await store.get(configKey)
       const config = JSON.parse(encodedValue.toString())
       if (key !== undefined && !_has(config, key)) {
-        throw new Error(`Key ${key} does not exist in config`)
+        throw new errors.NotFoundError(`Key ${key} does not exist in config`)
       }
 
       const value = key !== undefined ? _get(config, key) : config

src/errors/index.js

@@ -1,5 +1,20 @@
 'use strict'
 
+/**
+ * Error raised when requested item is not found.
+ */
+class NotFoundError extends Error {
+  constructor (message) {
+    super(message)
+    this.name = 'NotFoundError'
+    this.code = 'ERR_NOT_FOUND'
+    this.message = message
+  }
+}
+
+NotFoundError.code = 'ERR_NOT_FOUND'
+exports.NotFoundError = NotFoundError
+
 exports.ERR_REPO_NOT_INITIALIZED = 'ERR_REPO_NOT_INITIALIZED'
 exports.ERR_REPO_ALREADY_OPEN = 'ERR_REPO_ALREADY_OPEN'
 exports.ERR_REPO_ALREADY_CLOSED = 'ERR_REPO_ALREADY_CLOSED'