Gemfile states gem 'racc', without any particular spec.

$ bundle
[...]
Using racc 1.5.0 (java)
[...]
$ bundle exec racc ...
bundler: command not found: racc
Install missing gem executables with `bundle install`
rake aborted!

Same config appears to run without an issue on jruby
See full CI spec (github actions): https://github.com/rubocop-hq/rubocop-ast/pull/128/checks?check_run_id=1178552900

Reproduced on my mac too.