Ruby on railsでの自動デプロイ不具合の解決

前提・実現したいこと

Ruby on railsで簡易チャットツール（Chatspace)を作っています。
経緯として、実装中にrails s でlocal hostを立ち上げた際log_to_stdout': undefined method　formatter' for nil:NilClass (NoMethodError) とエラーが出たと同時にほとんどのrbファイルが消えてしまったため再度ファイルを作り直しました。全てファイルを作り再度、自動デプロイを行なった際、複雑なエラーが出てしまったので、どのように解決すれば良いかご教示願います。自動デプロイ機能を実装中に以下のエラーメッセージが発生しました。

発生している問題・エラーメッセージ

$ bundle exec cap production deploy
00:00 deploy:upload
Uploading config/secrets.yml 100.0%
〜省略〜

00:13 deploy:migrate
[deploy:migrate] Run rake db:migrate
00:13 deploy:migrating
01 $HOME/.rbenv/bin/rbenv exec bundle exec rake db:migrate
01 rake aborted!
01 StandardError: An error has occurred, all later migrations canceled:
01
01 Index name 'index_groups_on_name' on table 'groups' already exists
省略

  01 Caused by:
  01 ArgumentError: Index name 'index_groups_on_name' on table 'groups' alr…
 省略

  01 Tasks: TOP => db:migrate
  01 (See full trace by running task with --trace)
  01 == 20191022004145 CreateGroups: migrating ============================…
  01 -- create_table(:groups)

<Thread:0x00007fe8ab6b42e8@/Users/katsuyukiishizaki/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sshkit-1.20.0/lib/sshkit/runners/parallel.rb:10 run> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
1: from /Users/katsuyukiishizaki/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sshkit-1.20.0/lib/sshkit/runners/parallel.rb:11:in block (2 levels) in execute' /Users/katsuyukiishizaki/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sshkit-1.20.0/lib/sshkit/runners/parallel.rb:15:in rescue in block (2 levels) in execute': Exception while executing as ec2-user@18.176.24.254: rake exit status: 1 (SSHKit::Runner::ExecuteError)
rake stdout: == 20191022004145 CreateGroups: migrating =====================================
-- create_table(:groups)
rake stderr: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Index name 'index_groups_on_name' on table 'groups' already exists
省略

Caused by:
ArgumentError: Index name 'index_groups_on_name' on table 'groups' already exists
省略
<Thread:0x00007fe8ab6b5eb8@/Users/katsuyukiishizaki/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sshkit-1.20.0/lib/sshkit/runners/parallel.rb:10 run> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
1: from /Users/katsuyukiishizaki/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sshkit-1.20.0/lib/sshkit/runners/parallel.rb:11:in block (2 levels) in execute' /Users/katsuyukiishizaki/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/sshkit-1.20.0/lib/sshkit/runners/parallel.rb:15:in rescue in block (2 levels) in execute': Exception while executing as ec2-user@18.176.24.254: Exception while executing as ec2-user@18.176.24.254: rake exit status: 1 (SSHKit::Runner::ExecuteError)
rake stdout: == 20191022004145 CreateGroups: migrating =====================================
-- create_table(:groups)
rake stderr: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Index name 'index_groups_on_name' on table 'groups' already exists
省略
Caused by:
ArgumentError: Index name 'index_groups_on_name' on table 'groups' already exists
省略

Tasks: TOP => db:migrate
(See full trace by running task with --trace)
(Backtrace restricted to imported tasks)
cap aborted!
SSHKit::Runner::ExecuteError: Exception while executing as ec2-user@18.176.24.254: Exception while executing as ec2-user@18.176.24.254: rake exit status: 1
rake stdout: == 20191022004145 CreateGroups: migrating =====================================
-- create_table(:groups)
rake stderr: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Index name 'index_groups_on_name' on table 'groups' already exists
省略

Caused by:
ArgumentError: Index name 'index_groups_on_name' on table 'groups' already exists
省略

Caused by:
SSHKit::Runner::ExecuteError: Exception while executing as ec2-user@18.176.24.254: rake exit status: 1
rake stdout: == 20191022004145 CreateGroups: migrating =====================================
-- create_table(:groups)
rake stderr: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Index name 'index_groups_on_name' on table 'groups' already exists

省略
Caused by:
ArgumentError: Index name 'index_groups_on_name' on table 'groups' already exists
省略
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

Caused by:
SSHKit::Command::Failed: rake exit status: 1
rake stdout: == 20191022004145 CreateGroups: migrating =====================================
-- create_table(:groups)
rake stderr: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Index name 'index_groups_on_name' on table 'groups' already exists
省略

Caused by:
ArgumentError: Index name 'index_groups_on_name' on table 'groups' already exists
省略

Tasks: TOP => db:migrate
(See full trace by running task with --trace)

Tasks: TOP => deploy:migrate
(See full trace by running task with --trace)
The deploy has failed with an error: Exception while executing as ec2-user@18.176.24.254: Exception while executing as ec2-user@18.176.24.254: rake exit status: 1
rake stdout: == 20191022004145 CreateGroups: migrating =====================================
-- create_table(:groups)
rake stderr: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

Index name 'index_groups_on_name' on table 'groups' already exists
省略

Caused by:
ArgumentError: Index name 'index_groups_on_name' on table 'groups' already exists
省略

Tasks: TOP => db:migrate
(See full trace by running task with --trace)

** DEPLOY FAILED
** Refer to log/capistrano.log for details. Here are the last 20 lines:

省略

/home/ec2-user/.rbenv/versions/2.5.1/bin/bundle:23:in `load'

/home/ec2-user/.rbenv/versions/2.5.1/bin/bundle:23:in `<main>'

DEBUG [9296744a] Tasks: TOP => db:migrate

DEBUG [9296744a] (See full trace by running task with --trace)

DEBUG [9296744a] == 20191022004145 CreateGroups: migrating =====================================

-- create_table(:groups)

ishikounoMacBook-Air:chat-space katsuyukiishizaki$

該当のソースコード

試したこと

1　現在のインスタンス上のchat-spaceのdbをdropする。
ec2-user@ip-172-31-40-85 chat-space]$ rails db:drop
その後chat-spaceのディレクトリを削除。
[ec2-user@ip-172-31-40-85 chat-space]$ rm -rf chat-space

2　その後、gitとの連携を行う
3　その後まずは手動デプロイを行う。そのためにunicorn.rbの記述を手動デプロイ時の状態に変更しておく。
4　手動デプロイまで行えたら、おそらくcssがうまく効いていないのでアセットコンパイルも行う。
その後はnginx、capistranoの導入は済んでいるので、unicorn.rbの記述を自動デプロイの記述に直したら自動デプロイを実行。