Error: undefined method `last' for nil:NilClass (NoMethodError)

[elado]

I'm running my app (not on Rails, just config.ru) and getting this:

/gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:352:in `initialize': undefined method `last' for nil:NilClass (NoMethodError)
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:131:in `new'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:131:in `node_for'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:171:in `block in initialize'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:171:in `map'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:171:in `initialize'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:131:in `new'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:131:in `node_for'
    from /gems/grape-reload-0.0.4/lib/ripper/extract_constants.rb:393:in `extract_constants'
    from /gems/grape-reload-0.0.4/lib/grape/reload/dependency_map.rb:27:in `block in initialize'
    from /gems/grape-reload-0.0.4/lib/grape/reload/dependency_map.rb:27:in `map'
    from /gems/grape-reload-0.0.4/lib/grape/reload/dependency_map.rb:27:in `initialize'
    from /gems/grape-reload-0.0.4/lib/grape/reload/dependency_map.rb:129:in `new'
    from /gems/grape-reload-0.0.4/lib/grape/reload/dependency_map.rb:129:in `initialize'
    from /gems/grape-reload-0.0.4/lib/grape/reload/rack_builder.rb:73:in `new'
    from /gems/grape-reload-0.0.4/lib/grape/reload/rack_builder.rb:73:in `boot!'

Refers to @module_name = args.find{|a| a.first == :const_ref}.last[1]

The args is:

{
  :args => [
    [0] [
      [0] :const_path_ref,
      [1] [
        [0] :const_path_ref,
        [1] [
          [0] :var_ref,
          [1] [
            [0] :@const,
            [1] "CarrierWave",
            [2] [
              [0] 54,
              [1] 7
            ]
          ]
        ],
        [2] [
          [0] :@const,
          [1] "Sequel",
          [2] [
            [0] 54,
            [1] 20
          ]
        ]
      ],
      [2] [
        [0] :@const,
        [1] "Validations",
        [2] [
          [0] 54,
          [1] 28
        ]
      ]
    ],
    [1] [
      [0] :bodystmt,
      [1] [
        [0] [
          [0] :void_stmt
        ],
        [1] [
          [0] :def,
          [1] [
            [0] :@ident,
            [1] "validate",
            [2] [
              [0] 55,
              [1] 6
            ]
          ],
          [2] [
            [0] :params,
            [1] nil,
            [2] nil,
            [3] nil,
            [4] nil,
            [5] nil,
            [6] nil,
            [7] nil
          ],
          [3] [
            [0] :bodystmt,
            [1] [
              [0] [
                [0] :zsuper
              ],
              [1] [
                [0] :method_add_block,
                [1] [
                  [0] :call,
                  [1] [
                    [0] :call,
                    [1] [
                      [0] :call,
                      [1] [
                        [0] :var_ref,
                        [1] [
                          [0] :@kw,
                          [1] "self",
                          [2] [
                            [0] 57,
                            [1] 4
                          ]
                        ]
                      ],
                      [2] :".",
                      [3] [
                        [0] :@ident,
                        [1] "class",
                        [2] [
                          [0] 57,
                          [1] 9
                        ]
                      ]
                    ],
                    [2] :".",
                    [3] [
                      [0] :@ident,
                      [1] "uploaders",
                      [2] [
                        [0] 57,
                        [1] 15
                      ]
                    ]
                  ],
                  [2] :".",
                  [3] [
                    [0] :@ident,
                    [1] "each_key",
                    [2] [
                      [0] 57,
                      [1] 25
                    ]
                  ]
                ],
                [2] [
                  [0] :do_block,
                  [1] [
                    [0] :block_var,
                    [1] [
                      [0] :params,
                      [1] [
                        [0] [
                          [0] :@ident,
                          [1] "column",
                          [2] [
                            [0] 57,
                            [1] 38
                          ]
                        ]
                      ],
                      [2] nil,
                      [3] nil,
                      [4] nil,
                      [5] nil,
                      [6] nil,
                      [7] nil
                    ],
                    [2] false
                  ],
                  [2] [
                    [0] [
                      [0] :if_mod,
                      [1] [
                        [0] :method_add_arg,
                        [1] [
                          [0] :fcall,
                          [1] [
                            [0] :@ident,
                            [1] "send",
                            [2] [
                              [0] 58,
                              [1] 39
                            ]
                          ]
                        ],
                        [2] [
                          [0] :arg_paren,
                          [1] [
                            [0] :args_add_block,
                            [1] [
                              [0] [
                                [0] :string_literal,
                                [1] [
                                  [0] :string_content,
                                  [1] [
                                    [0] :string_embexpr,
                                    [1] [
                                      [0] [
                                        [0] :var_ref,
                                        [1] [
                                          [0] :@ident,
                                          [1] "column",
                                          [2] [
                                            [0] 58,
                                            [1] 47
                                          ]
                                        ]
                                      ]
                                    ]
                                  ],
                                  [2] [
                                    [0] :@tstring_content,
                                    [1] "_integrity_error",
                                    [2] [
                                      [0] 58,
                                      [1] 54
                                    ]
                                  ]
                                ]
                              ]
                            ],
                            [2] false
                          ]
                        ]
                      ],
                      [2] [
                        [0] :method_add_arg,
                        [1] [
                          [0] :call,
                          [1] [
                            [0] :vcall,
                            [1] [
                              [0] :@ident,
                              [1] "errors",
                              [2] [
                                [0] 58,
                                [1] 6
                              ]
                            ]
                          ],
                          [2] :".",
                          [3] [
                            [0] :@ident,
                            [1] "add",
                            [2] [
                              [0] 58,
                              [1] 13
                            ]
                          ]
                        ],
                        [2] [
                          [0] :arg_paren,
                          [1] [
                            [0] :args_add_block,
                            [1] [
                              [0] [
                                [0] :var_ref,
                                [1] [
                                  [0] :@ident,
                                  [1] "column",
                                  [2] [
                                    [0] 58,
                                    [1] 17
                                  ]
                                ]
                              ],
                              [1] [
                                [0] :string_literal,
                                [1] [
                                  [0] :string_content,
                                  [1] [
                                    [0] :@tstring_content,
                                    [1] "invalid",
                                    [2] [
                                      [0] 58,
                                      [1] 26
                                    ]
                                  ]
                                ]
                              ]
                            ],
                            [2] false
                          ]
                        ]
                      ]
                    ]
                  ]
                ]
              ]
            ],
            [2] nil,
            [3] nil,
            [4] nil
          ]
        ]
      ],
      [2] nil,
      [3] nil,
      [4] nil
    ]
  ]
}

It refers to source of gem carrierwave-sequel.

[AMar4enko]

Wow, looks weird.
Can you show you config.ru and Gemfile? It's should't even try to parse gems sources.

[elado]

My bad, it was referring my code, which is

module CarrierWave::Sequel::Validations
  def validate
    super
    self.class.uploaders.each_key do |column|
      errors.add(column, 'invalid') if send("#{column}_integrity_error")
    end
  end
end

Once removed it failed on something else, similar: an already-defiend module with an instance method.

My config.ru is something like:

require_relative './server'
require 'grape/reload'

Grape::RackBuilder.setup do
  logger Logger.new(STDOUT)
  add_source_path File.expand_path('**/*.rb', __dir__)
  reload_threshold 1
  force_reloading true
  mount 'MyApp::API', to: '/'
end

run Grape::RackBuilder.boot!.application

[AMar4enko]

Can you add test reproducing error?
BTW, in readme i describe such potential issue:

# Bad
class AlreadyDefined
# Here is your code to patch class
end

# Good
AlreadyDefined.class_eval do 
# Here is your code to patch class
end