错误日志：

\jsx> yarn start
yarn run v1.19.1
$ node ./YarnStartPreCheck.js && react-app-rewired start
internal/modules/cjs/loader.js:797
    throw err;
    ^

Error: Cannot find module 'webpack/lib/node/NodeTemplatePlugin'
Require stack:
- D:………………\jsx\node_modules\html-webpack-plugin\lib\compiler.js
- D:………………\jsx\node_modules\html-webpack-plugin\index.js
- D:………………\jsx\node_modules\react-scripts\config\webpack.config.js
- D:………………\jsx\node_modules\react-app-rewired\scripts\start.js
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:794:15)
    at Function.Module._load (internal/modules/cjs/loader.js:687:27)
    at Module.require (internal/modules/cjs/loader.js:849:19)
    at require (internal/modules/cjs/helpers.js:74:18)
    at Object.<anonymous> (D:………………\jsx\node_modules\html-webpack-plugin\lib\compiler.js:14:28)
    at Module._compile (internal/modules/cjs/loader.js:956:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:973:10)
    at Module.load (internal/modules/cjs/loader.js:812:32)
    at Function.Module._load (internal/modules/cjs/loader.js:724:14)
    at Module.require (internal/modules/cjs/loader.js:849:19) {
  code: 'MODULE_NOT_FOUND',
  requireStack: [
    'D:\\……………………\\jsx\\node_modules\\html-webpack-plugin\\lib\\compiler.js',
    'D:\\………………\\jsx\\node_modules\\html-webpack-plugin\\index.js',
    'D:\\………………\\jsx\\node_modules\\react-scripts\\config\\webpack.config.js',
    'D:\\………………\\jsx\\node_modules\\react-app-rewired\\scripts\\start.js'
  ]
}
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

　　

撤销代码修改、配置修改，yarn start，错误同上（非代码、配置问题）

 

重新安装yarn： yarn install，错误同上（非 yarn版本问题）。

 

查找.gitignore文件：

# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.

# dependencies
/node_modules
/dist
/__MOCK__
/.pnp
.pnp.js
/src/index.js

# testing
/coverage

# production
/build

# misc
.DS_Store
.env.local
.env.development.local
.env.test.local
.env.production.local

npm-debug.log*
yarn-debug.log*
yarn-error.log*
yarn.lock

　　

 

删除文件夹：node_modules & dist

重新安装yarn： yarn install  （yarn install //安装package.json里所有包，并将包及它的所有依赖项保存进yarn.lock）

重新运行：成功  （maybe：包安装冲突 or 包缺失）