Windows の場合、以下作業が必要な場合があります。

node.jsのエラー解決方法

my_project> npx create-react-app client
Need to install the following packages:
  create-react-app
Ok to proceed? (y) y
npm WARN deprecated tar@2.2.2: This version of tar is no longer supported, and will not receive security updates. Please upgrade asap.
 
Creating a new React app in C:\Users\shinobu\NoNameSeminer\ethereum\my_project\client.
 
Installing packages. This might take a couple of minutes.
Installing react, react-dom, and react-scripts with cra-template...
 
 
added 1379 packages in 7m
 
176 packages are looking for funding
  run `npm fund` for details
 
Initialized a git repository.
 
Installing template dependencies using npm...
npm WARN deprecated source-map-resolve@0.6.0: See https://github.com/lydell/source-map-resolve#deprecated
 
added 39 packages in 42s
 
176 packages are looking for funding
  run `npm fund` for details
Removing template package using npm...
 
 
removed 1 package, and audited 1418 packages in 17s
 
176 packages are looking for funding
  run `npm fund` for details
 
6 moderate severity vulnerabilities
 
To address all issues (including breaking changes), run:
  npm audit fix --force
 
Run `npm audit` for details.
 
Created git commit.
 
Success! Created client at C:\Users\shinobu\NoNameSeminer\ethereum\my_project\client
Inside that directory, you can run several commands:
 
  npm start
    Starts the development server.
 
  npm run build
    Bundles the app into static files for production.
 
  npm test
    Starts the test runner.
 
  npm run eject
    Removes this tool and copies build dependencies, configuration files
    and scripts into the app directory. If you do this, you can’t go back!
 
We suggest that you begin by typing:
 
  cd client
  npm start
 
Happy hacking!
PS C:\Users\shinobu\NoNameSeminer\ethereum\my_project>