CircleCIでのビルドが通らず困っています

実現したいこと

Docker-composeで環境構築をしたRailsのアプリを、CircleCIを使ってリモートリポジトリにpushする際に、自動テストを走らせたいと思っています。

しかし、CircleCIをビルドしようとすると下記のエラーが出力されます。テストコード以外のコードに対するエラーなのではないかと思っているのですが、なかなか糸口が掴めません。

発生している問題・エラーメッセージ

#!/bin/bash -eo pipefail
mkdir /tmp/test-results
TEST_FILES="$(circleci tests glob "spec/**/*_spec.rb" | \
circleci tests split --split-by=timings)"

bundle exec rspec \
--format progress \
--format RspecJunitFormatter \
--out /tmp/test-results/rspec.xml \
--format progress \
$TEST_FILES
Error reading historical timing data: file does not exist
Requested weighting by historical based timing, but they are not present. Falling back to weighting by name.
/home/circleci/komarigoto_hiroba/vendor/bundle/ruby/2.7.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/helper.rb:355: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
/home/circleci/komarigoto_hiroba/vendor/bundle/ruby/2.7.0/gems/sprockets-4.0.2/lib/sprockets/base.rb:118: warning: The called method `[]' is defined here
F

Failures:

  1) Users GET /new returns http success
     Failure/Error: <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
     
     ActionView::Template::Error:
       Webpacker can't find application in /home/circleci/komarigoto_hiroba/public/packs-test/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:
       {
       }
     # ./app/views/layouts/application.html.erb:8:in `_app_views_layouts_application_html_erb__2870217039742820957_24220'
     # ./spec/requests/users_request_spec.rb:7:in `block (3 levels) in <main>'
     # ------------------
     # --- Caused by: ---
     # Webpacker::Manifest::MissingEntryError:
     #   Webpacker can't find application in /home/circleci/komarigoto_hiroba/public/packs-test/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:
     #   {
     #   }
     #   ./app/views/layouts/application.html.erb:8:in `_app_views_layouts_application_html_erb__2870217039742820957_24220'

Finished in 4.77 seconds (files took 3.44 seconds to load)
1 example, 1 failure

Failed examples:

rspec ./spec/requests/users_request_spec.rb:6 # Users GET /new returns http success


Exited with code exit status 1

該当のソースコード

config.yml

version: 2
jobs:
    build:
        docker:
            - image: circleci/ruby:2.7.1-node-browsers
              environment:
                - BUNDLER_VERSION: 2.1.4
                - RAILS_ENV: 'test'

            - image: circleci/mysql:5.7
              environment:
                - MYSQL_ALLOW_EMPTY_PASSWORD: 'true'
                - MYSQL_ROOT_HOST: '127.0.0.1'

        working_directory: ~/komarigoto_hiroba


        steps:
        - checkout

        - restore_cache:
            keys:
            - v1-dependencies-{{ checksum "Gemfile.lock" }}
            - v1-dependencies-

        - run:
            name: install dependencies
            command: |
                gem install bundler -v 2.1.4
                bundle install --jobs=4 --retry=3 --path vendor/bundle

        - save_cache:
            paths:
            - ./vendor/bundle
            key: v1-dependencies-{{ checksum "Gemfile.lock" }}

        # Database setup
        - run: mv ./config/database.yml.ci ./config/database.yml

        #- run: NODE_ENV=test bundle exec rails webpacker:compile
        # Database setup
        - run:
            name: Databasesetup
            command: |
                bundle exec rake db:create
                bundle exec rake db:schema:load

        # run tests!
        - run:
            name: Run rspec
            command: |
                mkdir /tmp/test-results
                TEST_FILES="$(circleci tests glob "spec/**/*_spec.rb" | \
                circleci tests split --split-by=timings)"

                bundle exec rspec \
                --format progress \
                --format RspecJunitFormatter \
                --out /tmp/test-results/rspec.xml \
                --format progress \
                $TEST_FILES

        # collect reports
        - store_test_results:
            path: /tmp/test-results
        - store_artifacts:
            path: /tmp/test-results
            destination: test-results

manifest.json

{
  "application.js": "/packs/js/application-9afcbb5693aa87623e69.js",
  "application.js.map": "/packs/js/application-9afcbb5693aa87623e69.js.map",
  "entrypoints": {
    "application": {
      "js": [
        "/packs/js/application-9afcbb5693aa87623e69.js"
      ],
      "js.map": [
        "/packs/js/application-9afcbb5693aa87623e69.js.map"
      ]
    }
  }
}

application.html.erb

ruby:application.html.erb
1<!DOCTYPE html>
2<html>
3  <head>
4    <title>komarigoto-hiroba</title>
5    <%= csrf_meta_tags %>
6    <%= csp_meta_tag %>
7    <%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>
8    <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
9    <%= render 'layouts/shim' %>
10  </head>
11  <body>
12    <%= render 'layouts/header' %>
13    <div class=""></div>
14    <div class="container">
15      <%= yield %>
16    </div>
17  </body>
18</html>

試したこと

application.html.erbの

<%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>
<%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
の2行を消してみる

→消すとbootstrapなどを読み込まなくなる