我尝试在运行 calabash-ios 脚本时启动 firefox 浏览...但是它会引发以下错误：
#<ArgumentError: wrong number of arguments (0 for 1)>
/gems/ruby-1.9.3-p448/gems/calabash-cucumber-0.9.155/lib/calabash-cucumber/operations.rb:67:in `tap'
/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/rexml/parsers/baseparser.rb:183:in `pull'
/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/rexml/parsers/treeparser.rb:22:in `parse'
/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/rexml/document.rb:245:in `build'
/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/rexml/document.rb:43:in `initialize'
/gems/ruby-1.9.3-p448/gems/selenium-webdriver-2.35.1/lib/selenium/webdriver/firefox/extension.rb:44:in `new'
/gems/ruby-1.9.3-p448/gems/selenium-webdriver-2.35.1/lib/selenium/webdriver/firefox/extension.rb:44:in `read_id_from_install_rdf'
我可以单独启动一个firefox浏览器，而不需要使用calabash脚本。
如何克服这个问题？