エラー:Rubocopをダウンロードしようとしたときにgem native extensionのビルドに失敗しました
「sudo gem install rubocop」を試してみると... Building native extensions. This could take a while... ERROR: Error installing rubocop: ERROR: Failed to build gem native extension. current directory: /var/lib/gems/2.3.0/gems/rainbow-2.2.1/ext /usr/bin/ruby2.3 mkrf_conf.rb current directory: /var/lib/gems/2.3.0/gems/rainbow-2.2.1/ext /usr/bin/ruby2.3 -rubygems /usr/share/rubygems-integration/all/gems/rake-10.5.0/bin/rake RUBYARCHDIR=/var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rainbow-2.2.1 RUBYLIBDIR=/var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rainbow-2.2.1 /usr/bin/ruby2.3: No such file or directory -- /usr/share/rubygems-integration/all/gems/rake-10.5.0/bin/rake (LoadError) rake failed, exit code 1 …