在创建了一个类型为typescript模板的新应用npx create-react-app my-app --template typescript之后，当我执行yarn start时，它无法启动。错误如下：

yarn run v1.22.10
  $ react-scripts start
  We detected TypeScript in your project (src/App.test.tsx) and created a tsconfig.json file for you.
  
  It looks like you're trying to use TypeScript but do not have typescript installed.
  Please install typescript by running yarn add typescript.
  If you are not trying to use TypeScript, please remove the tsconfig.json file from your package root (and any TypeScript files).
  
  error Command failed with exit code 1.
  info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

版本如下：
npm 7.11.2
yarn 1.22.10
node v14.13.1
只有在执行了yarn add typescript web-vitals和yarn add -D @types/react @types/react-dom之后，它才正常工作。