Heroku Precompiling assets failed "Webpack not found"

[shahid-waris]

remote: Compiling...
remote: Compilation failed:
remote: yarn run v1.22.19
remote: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
remote:
remote:
remote: error Command "webpack" not found.
remote:
remote:
remote: !
remote: ! Precompiling assets failed.
remote: !
remote: ! Push rejected, failed to compile Ruby app.
remote:
remote: ! Push failed
remote: Verifying deploy...
remote:
remote: ! Push rejected to eminabadi.
remote:
To https://git.heroku.com/eminabadi.git
! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/eminabadi.git'

[shahid-waris]

Deploying on Heroku stack:20