当我尝试在Rubymine中运行程序时，我得到了NoMethodError。
有这个错误的描述：
/Users/admin/.rvm/gems/ruby-2.1.2@global/gems/sequel-4.11.0/lib/sequel/plugins/json_serializer.rb:166:in `<module:ClassMethods>': undefined method `inherited_instance_variables' for Sequel::Plugins:Module (NoMethodError)
/Users/admin/.rvm/gems/ruby-2.1.2@global/gems/sequel-4.11.0/lib/sequel/plugins/json_serializer.rb:166:in `<module:ClassMethods>': undefined method `inherited_instance_variables' for Sequel::Plugins:Module (NoMethodError)
from /Users/admin/.rvm/gems/ruby-2.1.2@global/gems/sequel-4.11.0/lib/sequel/plugins/json_serializer.rb:136:in `<module:JsonSerializer>'
from /Users/admin/.rvm/gems/ruby-2.1.2@global/gems/sequel-4.11.0/lib/sequel/plugins/json_serializer.rb:111:in `<module:Plugins>'
from /Users/admin/.rvm/gems/ruby-2.1.2@global/gems/sequel-4.11.0/lib/sequel/plugins/json_serializer.rb:4:in `<module:Sequel>'
from /Users/admin/.rvm/gems/ruby-2.1.2@global/gems/sequel-4.11.0/lib/sequel/plugins/json_serializer.rb:3:in `<top (required)>'
from /Users/admin/Documents/Projects/marsu-schedule-server/json_generator/json_generator.rb:4:in `require'
from /Users/admin/Documents/Projects/marsu-schedule-server/json_generator/json_generator.rb:4:in `<top (required)>'
from /Users/admin/Documents/Projects/marsu-schedule-server/msu_server.rb:10:in `require'
from /Users/admin/Documents/Projects/marsu-schedule-server/msu_server.rb:10:in `<top (required)>'
from /Users/admin/Documents/Projects/marsu-schedule-server/app.rb:5:in `require'
from /Users/admin/Documents/Projects/marsu-schedule-server/app.rb:5:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'
执行终端（MAC OS X）会产生同样的错误。
提前致谢！