我正在尝试使用 gravatar_image_tag RoR 插件,当我启动 rails 控制台或 rails 服务器时,它给了我这个错误。我该怎么做才能修复它?
/Library/Ruby/Gems/1.8/gems/actionpack-3.1.0.beta1/lib/action_view/helpers/asset_tag_helpers/asset_paths.rb:66: uninitialized constant ActionView::Helpers::AssetTagHelper::AssetPaths::Mutex (NameError)
from /Library/Ruby/Gems/1.8/gems/actionpack-3.1.0.beta1/lib/action_view/helpers/asset_tag_helper.rb:3:in `require'
from /Library/Ruby/Gems/1.8/gems/actionpack-3.1.0.beta1/lib/action_view/helpers/asset_tag_helper.rb:3
from /Library/Ruby/Gems/1.8/gems/actionpack-3.1.0.beta1/lib/action_view/helpers.rb:39
from /Library/Ruby/Gems/1.8/gems/actionpack-3.1.0.beta1/lib/action_view/base.rb:134
from /Library/Ruby/Gems/1.8/gems/gravatar_image_tag-1.0.0/lib/gravatar_image_tag.rb:97
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler/runtime.rb:68:in `require'
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler/runtime.rb:68:in `require'
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler/runtime.rb:66:in `each'
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler/runtime.rb:66:in `require'
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler/runtime.rb:55:in `each'
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler/runtime.rb:55:in `require'
from /Library/Ruby/Gems/1.8/gems/bundler-1.0.13/lib/bundler.rb:120:in `require'
from /Users/pickhardt/projects/sample_app/config/application.rb:7
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0.beta1/lib/rails/commands.rb:51:in `require'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0.beta1/lib/rails/commands.rb:51
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0.beta1/lib/rails/commands.rb:48:in `tap'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0.beta1/lib/rails/commands.rb:48
from script/rails:6:in `require'
from script/rails:6