webpackerを使ったrailsアプリを実行するとき、TypeError: environment.plugins.set is not a functionというエラーが出る

環境

• Rails 5.1.5
• webpacker 3.3.0

現象

Compilation failed:
remote:        /tmp/build_074ca0ee678491d6f72035c60cc5f616/config/webpack/environment.js:5
remote:        environment.plugins.set('Provide',
remote:        ^
remote:        TypeError: environment.plugins.set is not a function
remote:        at Object.<anonymous> (/tmp/build_074ca0ee678491d6f72035c60cc5f616/config/webpack/environment.js:5:21)
remote:        at Module._compile (module.js:643:30)

対策

setではなくappendかprependを使う。webpacker 3.3.0でsetがremoveされたため。

例

Before

config/webpack/environment.js

environment.plugins.set('Provide',
  new webpack.ProvidePlugin({
    $: 'jquery',
    jQuery: 'jquery'
  })
)

After

config/webpack/environment.js

environment.plugins.prepend('Provide',
  new webpack.ProvidePlugin({
    $: 'jquery',
    jQuery: 'jquery'
  })
)

参考

https://github.com/rails/webpacker/issues/1318 https://github.com/rails/webpacker/blob/master/CHANGELOG.md#330---2018-03-03
http://more-caffeine.hatenablog.com/entry/2018/03/05/142450
https://stackoverflow.com/questions/49107725/i-got-webpacker-error-when-running-the-rails-app-typeerror-environment-plugin