ERROR custom keyword definition is invalid: data/errors should be boolean

• 1. 概要
• 2. 解決策
• 3. 詳細

1. 概要

Nuxt.js で新規のプロジェクト作成して実行しようとしたら下記のエラーが出ました．

 ERROR  custom keyword definition is invalid: data/errors should be boolean

2. 解決策

下記を実行すれば fix できました．

$ npm uninstall ajv
$ npm install ajv@6.8.1

3. 詳細

プロジェクトを新規作成

$ npx create-nuxt-app sample-003
? Project name sample-003
? Project description My stylish Nuxt.js project
? Use a custom server framework none
? Choose features to install
? Use a custom UI framework none
? Use a custom test framework none
? Choose rendering mode Universal
? Author name Hayato Akatsuka
? Choose a package manager npm

プロジェクト実行すると「 ERROR custom keyword definition is invalid: data/errors should be boolean」と怒られました．

$ cd sample-003
$ npm run dev

 WARN  Address `localhost:3000` is already in use.

ℹ Trying a random port...
 ERROR  custom keyword definition is invalid: data/errors should be boolean

  at Ajv.addKeyword (node_modules/ajv/lib/keyword.js:65:13)
  at module.exports (node_modules/ajv-errors/index.js:10:7)
  at Object.<anonymous> (node_modules/schema-utils/src/validateOptions.js:22:1)
  at Module._compile (internal/modules/cjs/loader.js:678:30)
  at Object.Module._extensions..js (internal/modules/cjs/loader.js:689:10)
  at Module.load (internal/modules/cjs/loader.js:589:32)
  at tryModuleLoad (internal/modules/cjs/loader.js:528:12)
  at Function.Module._load (internal/modules/cjs/loader.js:520:3)
  at Module.require (internal/modules/cjs/loader.js:626:17)
  at require (internal/modules/cjs/helpers.js:20:18)

本件については，webpack で issue が作成されていました．

• webpack broken by ajv@6.9.0, "custom keyword definition is invalid: data.errors should be boolean" · Issue #8768 · webpack/webpack

解決方法は ajv を下記の通りアンインストール後にインストールします．

$ npm uninstall ajv
$ npm install ajv@6.8.1

ちゃんと動きました．

$ npm run dev

 WARN  Address `localhost:3000` is already in use.
ℹ Trying a random port...
ℹ Preparing project for development                                                                                                                   ℹ Initial build may take a while                                                                                                                      ✔ Builder initialized                                                                                                                                 ✔ Nuxt files generated
✔ Client
  Compiled successfully in 8.39s
✔ Server
  Compiled successfully in 7.72s
ℹ Waiting for file changes

   ╭─────────────────────────────────────────────╮
   │                                             │
   │   Nuxt.js v2.4.3                            │
   │   Running in development mode (universal)   │
   │   Memory usage: 182 MB (RSS: 261 MB)        │
   │                                             │
   │   Listening on: http://localhost:50482      │
   │                                             │
   ╰─────────────────────────────────────────────╯