当rake db：命令执行时，显示错误

warning: parser/current is loading parser/ruby26, which recognizes
warning: 2.6.7-compliant syntax, but you are running 2.6.2.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.
C:/Ruby26-x64/bin/rake: No such file or directory - which yarn
rake aborted!
NoMethodError: undefined method `chomp' for nil:NilClass
C:/.../config/environment.rb:5:in `<main>'
Tasks: TOP => db:migrate => db:load_config => environment
(See full trace by running task with --trace)

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这发生在Windows10机器上，但Mac机器工作正常，没有错误。这是一个Ruby on Rails应用程序。这是环境。rb：

# Load the Rails application.
require_relative 'application'

# Initialize the Rails application.
Rails.application.initialize!

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如果你能帮忙的话，我将不胜感激。
编辑：使用--trace标志运行rake的输出，以查看NoMethodError的确切来源（rake --trace db:migrate）：

rake --trace db:migrate
warning: parser/current is loading parser/ruby26, which recognizes
warning: 2.6.7-compliant syntax, but you are running 2.6.2.
warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.
** Invoke db:migrate (first_time)
** Invoke db:load_config (first_time)
** Invoke environment (first_time)
** Execute environment
C:/Ruby26-x64/bin/rake: No such file or directory - which yarn
rake aborted!
NoMethodError: undefined method `chomp' for nil:NilClass
C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/mjml-rails-4.6.1/lib/mjml.rb:68:in `check_for_yarn_mjml_binary'
C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/mjml-rails-4.6.1/lib/mjml.rb:44:in `valid_mjml_binary'
C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/mjml-rails-4.6.1/lib/mjml/railtie.rb:13:in `block in <class:Railtie>'

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