尝试安装gem设计时出错

Question

我正在努力正确安装我的Gemfile。这是我的Gemfile。

source 'https://rubygems.org'
ruby '2.1.1'
git_source(:github) do |repo_name|
  repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
  "https://github.com/#{repo_name}.git"
end


gem 'rails', '~> 5.0.1'
gem 'sqlite3'
gem 'puma', '~> 3.0'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.2'
gem 'jquery-rails'
gem 'turbolinks', '~> 5'
gem 'jbuilder', '~> 2.5'


group :development, :test do
  gem 'byebug', platform: :mri
end

group :development do
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '~> 3.0.5'

  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'
end


gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

gem 'devise', '~> 4.2'

这是我试图运行的命令：

rails g devise:install

这是我得到的错误。

Running via Spring preloader in process 47142
Expected string default value for '--helper'; got true (boolean)
Expected string default value for '--assets'; got true (boolean)
Could not find generator 'devise:install'. Maybe you meant 'assets', 'generator' or 'coffee:assets'
Run `rails generate --help` for more options.

任何帮助将不胜感激！