herokuにpushした時のWARNING!をなんとかしたい−3

解決したいこと

railsとherokuを使って作ったアプリケーションをherokuにデプロイした際にでる、WARNING！を消したいです。
デプロイはできるのですが、herokuで開こうとした際に、Application Errorとなってしまいます。。

エラー内容

remote: -----> Pruning devDependencies
remote:        yarn install v1.12.0
remote:        [1/4] Resolving packages...
remote:        [2/4] Fetching packages...
remote:        [3/4] Linking dependencies...
remote:        [4/4] Building fresh packages...
remote:        warning Ignored scripts due to flag.
remote:        Done in 0.22s.
remote:
remote: -----> Build succeeded!
remote: -----> Discovering process types
remote:        Procfile declares types -> web
remote:
remote: -----> Compressing...
remote:        Done: 19.2M
remote: -----> Launching...
remote:        Released v12
remote:        https://rocky-ocean-42853.herokuapp.com/ deployed to Heroku
remote:

warning Ignored scripts due to flag.

この行が問題なのだと思うのですが、調べてもなかなか答えにたどり着けませんでした…
どなたかご教授いただけると幸いです(><)

追記

以下、heroku logs --tail　の結果です

2018-10-04T14:56:11.806755+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=rocky-ocean-42853.herok
uapp.com request_id=46092eb5-c29b-42fc-975a-4c653f9a8d07 fwd="61.210.125.130" dyno= connect= service= status=503 bytes= protocol=https
2018-10-04T15:03:20.166134+00:00 heroku[web.1]: State changed from crashed to starting
2018-10-04T15:03:23.597847+00:00 heroku[web.1]: Starting process with command `bundle exec puma -C config/puma.rb`
2018-10-04T15:03:27.149078+00:00 heroku[web.1]: Process exited with status 1
2018-10-04T15:03:27.163411+00:00 heroku[web.1]: State changed from starting to crashed
2018-10-04T15:03:26.981928+00:00 app[web.1]: /usr/lib/ruby/2.5.0/rubygems.rb:289:in `find_spec_for_exe': Could not find 'bundler' (1.1
7.0.pre.1) required by your /app/Gemfile.lock. (Gem::GemNotFoundException)
2018-10-04T15:03:26.981954+00:00 app[web.1]: To update to the lastest version installed on your system, run `bundle update --bundler`.
2018-10-04T15:03:26.981962+00:00 app[web.1]: from /usr/lib/ruby/2.5.0/rubygems.rb:263:in `bin_path'
2018-10-04T15:03:26.981956+00:00 app[web.1]: To install the missing version, run `gem install bundler:1.17.0.pre.1`
2018-10-04T15:03:26.981965+00:00 app[web.1]: from /app/bin/bundle:3:in `<main>'
2018-10-04T18:26:21.498136+00:00 heroku[web.1]: State changed from crashed to starting
2018-10-04T18:26:24.174723+00:00 heroku[web.1]: Starting process with command `bundle exec puma -C config/puma.rb`
2018-10-04T18:26:27.590086+00:00 heroku[web.1]: Process exited with status 1
2018-10-04T18:26:27.643429+00:00 heroku[web.1]: State changed from starting to crashed
2018-10-04T18:26:27.502357+00:00 app[web.1]: /usr/lib/ruby/2.5.0/rubygems.rb:289:in `find_spec_for_exe': Could not find 'bundler' (1.1
7.0.pre.1) required by your /app/Gemfile.lock. (Gem::GemNotFoundException)
2018-10-04T18:26:27.502460+00:00 app[web.1]: To update to the lastest version installed on your system, run `bundle update --bundler`.
2018-10-04T18:26:27.502463+00:00 app[web.1]: To install the missing version, run `gem install bundler:1.17.0.pre.1`
2018-10-04T18:26:27.510693+00:00 app[web.1]: from /usr/lib/ruby/2.5.0/rubygems.rb:263:in `bin_path'
2018-10-04T18:26:27.510739+00:00 app[web.1]: from /app/bin/bundle:3:in `<main>'

試したこと

logをみて、

bundle exec puma -C config/puma.rb

を実行しましたが、下のようにエラーが出てしまいました。

bundler: failed to load command: puma　(/Users/iharamoeka/.rbenv/versions/2.4.4/bin/puma)

puma.rbがおかしいのかと思い、確認してみました。

puma.rb
1threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
2threads threads_count, threads_count
3
4port        ENV.fetch("PORT") { 3000 }
5
6environment ENV.fetch("RAILS_ENV") { "development" }
7
8plugin :tmp_restart
9