我正在将Rails后端/反应前端应用程序部署到heroku。我在推向heroku master时遇到了这个错误：
remote: Both npm and yarn have created lockfiles for this application,
remote: but only one can be used to install dependencies. Installing
remote: dependencies using the wrong package manager can result in missing
remote: packages or subtle bugs in production.
remote:
remote: - To use npm to install your application's dependencies please delete
remote: the yarn.lock file.
remote:
remote: $ git rm yarn.lock
remote:
remote: - To use yarn to install your application's dependences please delete
remote: the package-lock.json file.
我删除了package-lock.json文件，但是当再次推送到heroku master时，我得到了：
fatal: 'heroku' does not appear to be a git repository
fatal: Could not read from remote repository.
Please make sure you have the correct access rights
出什么问题了？删除package.json之后，我是否跳过了一步？