任何人对我可能遇到此错误的原因有任何想法？我使用最新版本的watir-webdriver（0.5.3）
非常感谢。
irb(main):001:0> require 'watir-webdriver'
=> true
irb(main):002:0> b = Watir::Browser.new :chrome
Selenium::WebDriver::Error::WebDriverError: proxy must be of type dictionary, not null. Received: null
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/response.rb:45:in `assert_ok'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/response.rb:15:in `initialize'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/http/common.rb:54:in `new'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/http/common.rb:54:in `create_response'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/http/default.rb:64:in `request'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/http/common.rb:35:in `call'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/bridge.rb:410:in `raw_execute'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/bridge.rb:88:in `create_session'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/remote/bridge.rb:68:in `initialize'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/chrome/bridge.rb:22:in `initialize'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/common/driver.rb:35:in `new'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver/common/driver.rb:35:in `for'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/selenium-webdriver-2.8.0/lib/selenium/webdriver.rb:81:in `for'
from /Users/chris/.rvm/gems/ruby-1.9.2-p290/gems/watir-webdriver-0.3.5/lib/watir-webdriver/browser.rb:35:in `initialize'
from (irb):2:in `new'
from (irb):2
from /Users/chris/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `<main>'