尝试使用Ruby'canvas_cc'宝石创建.imscc墨盒，但是遇到了拍摄困难的问题。我按照自述文件中的基本文档进行操作，但是在gem中遇到了问题。

Ruby

require 'tmpdir'
course = CanvasCc::CanvasCC::Models::Course.new
course.identifier = "cc"
course.title =  "testing cc"
dir = Dir.mktmpdir
output_dir = CanvasCc::CanvasCC::CartridgeCreator.new(course).create(dir)

输出

Traceback (most recent call last):
        5: from course_creation.rb:25:in `<main>'
        4: from /Users/me/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/canvas_cc-0.0.43/lib/canvas_cc/canvas_cc/cartridge_creator.rb:18:in `create'
        3: from /Users/me/.rbenv/versions/2.5.1/lib/ruby/2.5.0/tmpdir.rb:89:in `mktmpdir'
        2: from /Users/me/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/canvas_cc-0.0.43/lib/canvas_cc/canvas_cc/cartridge_creator.rb:19:in `block in create'
        1: from /Users/me/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/canvas_cc-0.0.43/lib/canvas_cc/canvas_cc/cartridge_creator.rb:45:in `write_cartridge'
/Users/me/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/canvas_cc-0.0.43/lib/canvas_cc/canvas_cc/grading_standard_writer.rb:11:in `write': undefined method `empty?' for nil:NilClass (NoMethodError)

也尝试过

require 'canvas_cc'
course = CanvasCc::CanvasCC::Models::Course.new
course.identifier = "cc"
course.title =  "testing cc"
dir = Dir.mkdir "cartridge"
output_dir = CanvasCc::CanvasCC::CartridgeCreator.new(course).create(Dir.pwd + "/cartridge")

我在运行第二个脚本时遇到与第一个脚本相同的错误。

通过浏览文档和gem中的代码，我试图了解问题出在哪里，但是我似乎无法对其进行调试。我将Ruby 2.5.1和rbenv一起使用，但是我尝试了具有相同问题的其他多个ruby版本。

我的目标是仅使用此gem创建基本的通用墨盒，但我什至不能这样做。任何帮助将不胜感激！