Webpacker::Manifest::MissingEntryError in Devise::Sessions#newというエラーが出た時の解決法

#開発環境
・Rails 6.0.3.1
・Ruby 2.6.6

#エラー時の状況

$ rails s

コマンドを実行してlocalost3000にアクセスすると、

【エラー内容】


Webpacker::Manifest::MissingEntryError in Devise::Sessions#new
Showing /Users/XXXX_XXXX/Desktop/XXX_XXX_XXX/app/views/layouts/application.html.erb where line #9 raised:

Webpacker can't find application in /Users/XXXX_XXXX/Desktop/XXX_XXX_XXX/public/packs/manifest.json. Possible causes:
1. You want to set webpacker.yml value of compile to true for your environment
   unless you are using the `webpack -w` or the webpack-dev-server.
2. webpack has not yet re-run to reflect updates.
3. You have misconfigured Webpacker's config/webpacker.yml file.
4. Your webpack configuration is not creating a manifest.
Your manifest contains:

というエラーが出た。

該当部分は

application.html.erb

<%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>

と書いてある。

#解決方法

$ bundle exec rails webpacker:install

を実行したらエラーが解決できた。