-----> Build failed
! The 'yarnPath' could not be read from the 'yarnrc.yml' file It looks like 'yarnrc.yml' is missing the 'yarnPath' value, which is needed to identify the location of yarn for this build. To regenerate 'yarnrc.yml' with the 'yarnPath' value set, make sure Yarn 2 is installed on your local machine and set the version in your project directory with:
$ yarn set version berry
Read more at the Yarn docs: https://yarnpkg.com/getting-started/install#per-project-install
https://devcenter.heroku.com/articles/nodejs-support ! Push rejected, failed to compile Node.js app. ! Push failed