var execBundle: <Error class: unknown class>

If your project uses the Bundler requirements manager and your Rakefile doesn't load the bundler setup script, this option will allow you to launch rake tasks using the bundle exec command emulation. If you want to execute bundle install command, you need to do it in the Command Line step before the Rake step. Also, remember to set up the Ruby environment configurator build feature to automatically pass Ruby interpreter to the command line runner.