Hi, I tried to install open project on heroku. And followed the instructions gave by https://community.openproject.org/topics/959?board_id=6&r=3573#message-3573. But with no success. When deploying to Heroku I receive the following error:

$(npm bin)/webpack —config webpack.config.js
sh: 1: npm: not found
sh: 1: /webpack: not found
rake aborted!
Command failed with status (127): [$(npm bin)/webpack —config webpack.config…]
/tmp/build_addafd3a8b13336d55b30e0c7b60a02e/lib/tasks/assets.rake:47:in `block (2 levels) in <top (required)>’
Tasks: TOP => assets:precompile => assets:compile_environment => assets:webpack
(See full trace by running task with —trace)
!
! Precompiling assets failed.
!

! Push rejected, failed to compile Ruby app

To git@heroku.com:whispering-springs-1694.git
! [remote rejected] dev -> master (pre-receive hook declined)
error: failed to push some refs to ‘git@heroku.com:whispering-springs-1694.git’

Does anyone has any clue why I cant deploy? It works fine in localhost.
It seems that heroku cannot find npm? Why wouldnt heroku have npm installed?

Thanks for any help!