Repository: create-react-app
Issue: Type checks not working in a typescript project
Labels: stale,needs triage,issue: bug report

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### Describe the bug

`yarn start` or `yarn build` are not throwing any type errors.

### Did you try recovering your dependencies?

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I have tried a fresh install.

### Which terms did you search for in User Guide?

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I tried finding a similar issue in github, but there isn't any

### Environment

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```
Environment Info:

  current version of create-react-app: 4.0.3
  running from /home/kanagaraj/.config/yarn/global/node_modules/create-react-app

  System:
    OS: Linux 4.15 Ubuntu 18.04.4 LTS (Bionic Beaver)
    CPU: (4) x64 Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz
  Binaries:
    Node: 12.16.1 - /usr/bin/node
    Yarn: 1.21.1 - /usr/bin/yarn
    npm: 6.13.4 - /usr/bin/npm
  Browsers:
    Chrome: 86.0.4240.75
    Firefox: 89.0
  npmPackages:
    react: ^17.0.2 => 17.0.2 
    react-dom: ^17.0.2 => 17.0.2 
    react-scripts: 4.0.3 => 4.0.3 
  npmGlobalPackages:
    create-react-app: Not Found
```

### Steps to reproduce

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(Write your steps here:)

1. Run `npx create-react-app my-app --template typescript`
2. Create a new file `test.jsx` under the `src` directoy with following contents
```js
type Props = {
  message: string
}

export function getValue(props: Props): string {
  return props.message1
}
```
3. Update the index.tsx with following contens
```
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';
import {getValue} from "./test"

ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  document.getElementById('root')
);

// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();

console.log(getValue({message: "test"}))
```

4. Run `yarn start` or `yarn build`
5. No errors thrown even there is a type error in `test.jsx`

Code is present in this repo https://github.com/kanagarajkm/my-app-ts

### Expected behavior

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Type check errors should be thrown

### Actual behavior

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Type check errors are not thrown

### Reproducible demo

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Please refer this repo https://github.com/kanagarajkm/my-app-ts

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