I'm using Visual Studio 2019 and TypeScript 3.9.

I continued working on a React/.NET project when upon creating a few new tsx files Intellisence displayed a few errors, such as:

* `TS1259: [...] can only be default-imported using the 'esModuleInterop' flag`
* `TS2307: can not find module [...]`

The former shows up only in the new files, the latter in the `index.d.ts` file which a haven't modified since it worked the last time.

I verified:

* The correct tsconfig file is targeted (the project only contains one).
* I set the tsconfig file's build setting from 'None' to 'Contenct'.

Even after deleting the .vs folder and restarting VS it won't work.

EDIT: `"esModuleInterop": true` is also verified.

EDIT: Steps to reproduce:

1. Instal VS 2019 and Node.
2. Create a new React/.NET Core project in VS2019.
3. * Upgrade the react scripts to the latest with npm upgrade react-scripts --latest
4. Remove all eslinting packages with npm remove eslint eslint-config-react-app eslint-plugin-flowtype eslint-plugin-import eslint-plugin-jsx-a11y eslint-plugin-react¹
5. Install or upgrade TypeScript
6. To install TypeScript use npm install typscript --latest --save-dev
7. or if you already have TypeScript installed you can upgrade with npm upgrade TypeScript --latest
8. Install the TypeScript definition files with npm install @types/node @types/react @types/react-dom @types/react-router
9. Create the following tsconfig file:

```
  "include": [
    "src/*"
  ],
  "compilerOptions": {
    "target": "es5",
    "jsx": "react",
    "allowSyntheticDefaultImports": true,
    "lib": [
      "dom",
      "dom.iterable",
      "esnext"
    ],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true
  }
}

```

10. Create a new .tsx file and install and import some packages:

```
    import React, { Component } from 'react';
    import * as microsoftTeams from "@microsoft/teams-js";
    import { Button } from "@fluentui/react-northstar";
    import { AuthenticationContext, adalFetch, withAdalLogin } from 'react-adal';

```

It may or may not result in an TS2307 error.