ruby で制作したアプリを　herokuにpushすると「Precompiling assets failed.」とエラーが出る

前提・実現したいこと

Ruby on Rails でアプリを作成しローカル環境では正常に動作しました。
それをherokuをもちいてアップロードしたいです。

https://qiita.com/kazukimatsumoto/items/a0daa7281a3948701c39
を参考に操作を進めました。

発生している問題・エラーメッセージ

terminal
1git push heroku master

を実行すると

terminal
1remote: -----> Detecting rake tasks
2remote: -----> Preparing app for Rails asset pipeline
3remote:        Running: rake assets:precompile
4remote:        rake aborted!
5remote:        Sprockets::Railtie::ManifestNeededError: Expected to find a manifest file in `app/assets/config/manifest.js`
6remote:        But did not, please create this file and use it to link any assets that need
7remote:        to be rendered by your app:
8remote:        
9remote:        Example:
10remote:          //= link_tree ../images
11remote:          //= link_directory ../javascripts .js
12remote:          //= link_directory ../stylesheets .css
13remote:        and restart your server
14remote:        
15remote:        For more information see: https://github.com/rails/sprockets/blob/070fc01947c111d35bb4c836e9bb71962a8e0595/UPGRADING.md#manifestjs
16
17(中略)
18
19remote:  !     Precompiling assets failed.
20remote:  !
21remote:  !     Push rejected, failed to compile Ruby app.
22remote: 
23remote:  !     Push failed
24remote:  !
25remote:  ! ## Warning - The same version of this code has already been built: 54cb7a80eb8c20c1ec95267c9ae553c7f2a3d705
26remote:  !
27remote:  ! We have detected that you have triggered a build from source code with version 54cb7a80eb8c20c1ec95267c9ae553c7f2a3d705
28remote:  ! at least twice. One common cause of this behavior is attempting to deploy code from a different branch.
29remote:  !
30remote:  ! If you are developing on a branch and deploying via git you must run:
31remote:  !
32remote:  !     git push heroku <branchname>:main
33remote:  !
34remote:  ! This article goes into details on the behavior:
35remote:  !   https://devcenter.heroku.com/articles/duplicate-build-version
36remote: 
37remote: Verifying deploy...
38remote: 
39remote: !       Push rejected to <アプリ名>.
40remote: 
41To https://git.heroku.com/<アプリ名>.git
42 ! [remote rejected] master -> master (pre-receive hook declined)
43error: failed to push some refs to 'https://git.heroku.com/<アプリ名>.git'

と表示され実行できません。

試したこと

多くのサイトに以下の一文を足すと良いと書かれていたので実行しました

config/environments/production.rbへの記述


config.assets.initialize_on_precompile = false

全体はこのようなコードです。

config/environments/production.rb内


require_relative "boot"

require "rails/all"

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module <アプリ名>
  class Application < Rails::Application
    # Initialize configuration defaults for originally generated Rails version.
    config.load_defaults 6.1

    # Configuration for the application, engines, and railties goes here.
    #
    # These settings can be overridden in specific environments using the files
    # in config/environments, which are processed later.
    #
    # config.time_zone = "Central Time (US & Canada)"
    # config.eager_load_paths << Rails.root.join("extras")
    config.time_zone = 'Tokyo'

    #herokuの解決用
    config.assets.initialize_on_precompile = false
    
  end
end

怪しいのはターミナルのこのメッセージかなと思い、

terminal
1remote:        Running: rake assets:precompile
2remote:        rake aborted!
3remote:        Sprockets::Railtie::ManifestNeededError: Expected to find a manifest file in `app/assets/config/manifest.js`
4remote:        But did not, please create this file and use it to link any assets that need
5remote:        to be rendered by your app:
6remote:        
7remote:        Example:
8remote:          //= link_tree ../images
9remote:          //= link_directory ../javascripts .js
10remote:          //= link_directory ../stylesheets .css
11remote:        and restart your server

とりあえずExampleで示されている通りに変えてrails s でサーバを再起動しました。

js
1app/assets/config/manifest.js内のコード
2
3//= link_tree ../images
4//= link_directory ../javascripts .js　　
5//= link_directory ../stylesheets .css
6

もともとは2行目の//= link_directory ../javascripts .js　の記載がありませんでした。

他のサイトを参考に以下を実行すると

terminal
1$ RAILS_ENV=development bin/rails assets:precompile
2yarn install v1.22.10
3[1/4] ????  Resolving packages...
4[2/4] ????  Fetching packages...
5[3/4] ????  Linking dependencies...
6[4/4] ????  Building fresh packages...
7✨  Done in 2.54s.
8rails aborted!
9Sprockets::ArgumentError: link_directory argument must be a directory
10/app/assets/config/manifest.js:2
11Tasks: TOP => assets:precompile
12(See full trace by running task with --trace)