当我运行bundle install时，它会出现以下错误：
An error occurred while installing active_shipping (0.9.13), and Bundler cannot continue.
Make sure that `gem install active_shipping -v '0.9.13'` succeeds before bundling.
但是在运行gem install active_shipping -v '0.9.13'之前安装了bundle install。我该怎么办呢？谢谢！
xxxxxx:~/code/inventory$ gem install active_shipping -v '0.9.13'
Successfully installed active_shipping-0.9.13
1 gem installed
xxxxxx:~/code/inventory$ bundle install
Ignoring json-1.8.3 because its extensions are not built. Try: gem pristine json --version 1.8.3
/usr/lib/ruby/vendor_ruby/bundler.rb:284: warning: Insecure world writable dir /usr/local/bin in PATH, mode 040777
Fetching source index from https://rubygems.org/
Resolving dependencies...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Using rake (10.5.0)
Using Ascii85 (1.0.2)
Using ZenTest (4.9.5)
Using RubyInline (3.12.2)
Using i18n (0.7.0)
Using multi_json (1.11.3)
Using activesupport (3.2.22.2)
Using builder (3.0.4)
Using activemodel (3.2.22.2)
Using erubis (2.7.0)
Using journey (1.0.4)
Using rack (1.4.7)
Using rack-cache (1.6.1)
Using rack-test (0.6.3)
Using hike (1.2.3)
Using tilt (1.4.1)
Using sprockets (2.2.3)
Using actionpack (3.2.22.2)
Using mime-types (1.25.1)
Using polyglot (0.3.5)
Using treetop (1.4.15)
Using mail (2.5.4)
Using actionmailer (3.2.22.2)
Using active_utils (2.2.3)
Using json (1.8.3)
Using money (4.0.2)
Using macaddr (1.0.0)
Using uuid (2.3.7)
Using active_shipping (0.9.13) from git://github.com/optoro/active_shipping.git (at master)
NoMethodError: undefined method `spec' for nil:NilClass
An error occurred while installing active_shipping (0.9.13), and Bundler cannot continue.
Make sure that `gem install active_shipping -v '0.9.13'` succeeds before bundling.