RSpec導入後にRails g コマンドが使えなくなりました。

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リンク内容
こちらのサイトを参考にRSpecを導入してみたのですが、それからRails g コマンドが使えなくなってしまいました。

:~/environment/bootstrap_test (master) $ rails g model Tweet text:string title:string
/home/ec2-user/environment/bootstrap_test/config/application.rb:20:in `<top (required)>': undefined local variable or method `config' for main:Object (NameError)
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application.rb:92:in `require'
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application.rb:92:in `preload'
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application.rb:153:in `serve'
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application.rb:141:in `block in run'
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application.rb:135:in `loop'
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application.rb:135:in `run'
        from /home/ec2-user/.rvm/gems/ruby-2.6.3/gems/spring-2.0.2/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /home/ec2-user/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from /home/ec2-user/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from -e:1:in `<main>'

エラー文はこのようなもので、application.rbの記述したものがおかしかったのかな？と思いました。

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 BootstrapTest
  class Application < Rails::Application
    # Initialize configuration defaults for originally generated Rails version.
    config.load_defaults 5.1

    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration should go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded.
  end
end

config.generators do |g|
      g.test_framework :rspec,
                       fixtures: true,
                       view_specs: false,
                       helper_specs: false,
                       routing_specs: false,
                       controller_specs: true,
                       request_specs: false
      g.fixture_replacement :factory_bot, dir: "spec/factories"
end

source 'https://rubygems.org'

gem 'rails',        '5.1.6'
gem 'puma',         '3.9.1'
gem 'sass-rails',   '5.0.6'
gem 'bootstrap', '~> 4.1.1'
gem 'uglifier',     '3.2.0'
gem 'coffee-rails', '4.2.2'
gem 'jquery-rails', '4.3.1'
gem 'turbolinks',   '5.0.1'
gem 'jbuilder',     '2.6.4'

group :development, :test do
  gem 'sqlite3',      '1.3.13'
  gem 'byebug', '9.0.6', platform: :mri
  gem 'rspec-rails'
  gem 'factory_bot_rails'
  gem 'rails-controller-testing'
end

group :development do
  gem 'web-console',           '3.5.1'
  gem 'listen',                '3.1.5'
  gem 'spring',                '2.0.2'
  gem 'spring-watcher-listen', '2.0.1'
end

# Windows環境ではtzinfo-dataというgemを含める必要があります
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

rubyバージョン-2.6.3
railsバージョン-5.1.6
当方初学者で自力ではどうにもできませんでした。どなたかご教示お願い致します。