为什么heroku无法使我的构建失败，并说它在本地工作时找不到文件？

这里是按下heroku时发生的事情：

remote: -----> Build
remote:        Running build
remote:        
remote:        > [email protected] build /tmp/build_960f0e66a47347274538f4490dbb400d
remote:        > react-scripts build
remote:
remote:        Creating an optimized production build...
remote:        Failed to compile.
remote:
remote:        ./src/App.js
remote:        Cannot find file './pages/About' in './src'.
remote:
remote:
remote: npm ERR! code ELIFECYCLE
remote: npm ERR! errno 1
remote: npm ERR! [email protected] build: `react-scripts build`
remote: npm ERR! Exit status 1
remote: npm ERR!
remote: npm ERR! Failed at the [email protected] build script.
remote: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
remote:
remote: npm ERR! A complete log of this run can be found in:
remote: npm ERR!     /tmp/npmcache.7v0ee/_logs/2020-05-12T22_42_31_150Z-debug.log
remote:
remote: -----> Build failed
remote:        
remote:        We're sorry this build is failing! You can troubleshoot common issues here:
remote:        
remote:
remote:        If you're stuck, please submit a ticket so we can help:
remote:        /
remote:
remote:        Love,
remote:        Heroku
remote:
remote:  !     Push rejected, failed to compile Node.js app.
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote:
remote: !       Push rejected to boiling-island-73749.
remote:
To .git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to '.git'

它表示该构建失败，因为它找不到About.js。但是，我一直在本地打开我的应用程序，About.js表现得很好。我看不出为什么找不到该文件并导致构建失败。我还从heroku收到不同的消息，它要么无法指定节点版本，要么说“ engines.node中的危险semver范围（>）”。目前，我的package.json表示：

 "engines": {
    "node": "12.14.x",
    "npm": "6.x"
  }

有人知道我的构建为什么会不断失败并且拒绝推送到Heroku吗？