Error while deploying my app with NOW

Downloading 37 deployment files...
Installing build runtime...
Build runtime installed: 505.286ms
Looking up build cache...
Installing dependencies...
> core-js@2.6.11 postinstall /zeit/8357d63/node_modules/babel-runtime/node_modules/core-js
> node -e "try{require('./postinstall')}catch(e){}"
Thank you for using core-js ( https://github.com/zloirock/core-js ) for polyfilling JavaScript standard library!
The project needs your help! Please consider supporting of core-js on Open Collective or Patreon: 
> https://opencollective.com/core-js 
> https://www.patreon.com/zloirock 
Also, the author of core-js ( https://github.com/zloirock ) is looking for a good job -)
> core-js@3.6.4 postinstall /zeit/8357d63/node_modules/core-js
> node -e "try{require('./postinstall')}catch(e){}"
> core-js-pure@3.6.4 postinstall /zeit/8357d63/node_modules/core-js-pure
> node -e "try{require('./postinstall')}catch(e){}"
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.11 (node_modules/jest-haste-map/node_modules/fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.11: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.11 (node_modules/chokidar/node_modules/fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.11: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@2.1.2 (node_modules/fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@2.1.2: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})
added 1608 packages from 757 contributors in 21.735s
Running "npm run now-build"
> course-directory@0.1.0 now-build /zeit/8357d63
> react-scripts build && my build dist
Setting NODE_PATH to resolve modules absolutely has been deprecated in favor of setting baseUrl in jsconfig.json (or tsconfig.json if you are using TypeScript) and will be removed in a future major release of create-react-app.
Creating an optimized production build...
Compiled successfully.
File sizes after gzip:
  48.47 KB (-6 B)  build/static/js/2.cc722835.chunk.js
  5.14 KB (-14 B)  build/static/js/main.c774ea57.chunk.js
  1.05 KB          build/static/css/main.ceca84a1.chunk.css
  797 B            build/static/js/runtime-main.db9a898d.js
The project was built assuming it is hosted at /practice_React_Router/.
You can control this with the homepage field in your package.json.
The build folder is ready to be deployed.
To publish it at https://brandonwie.github.io/practice_React_Router/ , run:
  npm run deploy
Find out more about deployment here:
  bit.ly/CRA-deploy
sh: my: command not found
npm ERR! code ELIFECYCLE
npm ERR! syscall spawn
npm ERR! file sh
npm ERR! errno ENOENT
npm ERR! course-directory@0.1.0 now-build: `react-scripts build && my build dist`
npm ERR! spawn ENOENT
npm ERR! 
npm ERR! Failed at the course-directory@0.1.0 now-build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR!     /zeit/.npm/_logs/2020-01-21T08_36_47_305Z-debug.log
Error: Exited with 1
    at ChildProcess.child.on (/zeit/7783010c87aa68f0/.build-utils/.builder/node_modules/@now/static-build/dist/index.js:31880:24)
    at emitTwo (events.js:126:13)
    at ChildProcess.emit (events.js:214:7)
    at maybeClose (internal/child_process.js:925:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)
worker exited with code 20 and signal null
done