rails モデルを作ることができない(環境:cloud9)

問題

新しいモデルを作りたくコマンドを実行したのですが、以下の様なエラーが出てモデルを作ることができません。

ubuntu:~/environment/first_app (master) $ rails g model Country name:string
/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/actiontext-6.0.3/lib/action_text/engine.rb:47:in `block (2 levels) in <class:Engine>': uninitialized constant ActionText::Engine::ApplicationController (NameError)
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:428:in `instance_exec'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:428:in `block in make_lambda'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:200:in `block (2 levels) in halting'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:605:in `block (2 levels) in default_terminator'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:604:in `catch'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:604:in `block in default_terminator'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:201:in `block in halting'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:513:in `block in invoke_before'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:513:in `each'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:513:in `invoke_before'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/callbacks.rb:134:in `run_callbacks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/execution_wrapper.rb:119:in `complete!'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/execution_wrapper.rb:76:in `ensure in block in run!'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/execution_wrapper.rb:76:in `block in run!'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/execution_wrapper.rb:70:in `tap'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/execution_wrapper.rb:70:in `run!'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/execution_wrapper.rb:86:in `wrap'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3/lib/active_support/reloader.rb:51:in `reload!'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:168:in `serve'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:145:in `block in run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `loop'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from -e:1:in `<main>'

試したこと

PCの再起動
EC2の再起動
ブラウザをchromeからsafariへ変更

上の３つを試した理由は、cloud9そのものに問題があると考えたからです。
というのも、エラーの一番上の行に何やら書かれています。

/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/actiontext-6.0.3/lib/action_text/engine.rb:47:in `block (2 levels) in <class:Engine>': uninitialized constant ActionText::Engine::ApplicationController (NameError)

ApplicationControllerにエラーがありそうだったので、気になってファイルを覗こうとしました。
しかし、ファイルを開くことができません。以下の画像の様に、ファイルネーム横の円マークがグルグル周り続けるのです。