"npm run build" hangs with "UnhandledPromiseRejectionWarning", using TypeScript and a functional component with `defaultProps`

Is this a bug report?

Yes

Did you try recovering your dependencies?

Yes

$ npm --version
6.9.0

Environment

$ npx create-react-app --info

Environment Info:

  System:
    OS: Linux 4.15 Ubuntu 16.04.6 LTS (Xenial Xerus)
    CPU: x64 Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
  Binaries:
    Node: 10.15.3 - ~/.nvm/versions/node/v10.15.3/bin/node
    Yarn: 1.12.3 - /usr/bin/yarn
    npm: 6.9.0 - ~/.nvm/versions/node/v10.15.3/bin/npm
  Browsers:
    Chrome: flash.
Chromium 73.0.3683.75 Built on Ubuntu , running on Ubuntu 16.04
    Firefox: 66.0.1
  npmPackages:
    react: ^16.8.5 => 16.8.5 
    react-dom: ^16.8.5 => 16.8.5 
    react-scripts: 2.1.8 => 2.1.8 
  npmGlobalPackages:
    create-react-app: 2.1.8

Steps to Reproduce

This bug seems to require a fairly specific set of steps to reproduce it. I discovered it after upgrading my existing project from react-scripts 2.1.3 to 2.1.8, and after some effort, I was able to pinpoint which part of the project was causing the problem. I then reproduced the problem in minimal form.

The steps seem to be:

1. Set up a new Create React App project, with typescript.
2. Create one TypeScript source code file that declares an interface, and implements a function that uses that interface as its return type. Export the function, but not the interface.
3. Create another Typescript source code file, that implements a function. After the function body, add a static property to the function, that uses the return value of the function exported in step 2.
4. Save everything and run npm run build

Expected Behavior

The build process finishes successfully, in under 10 seconds, with output like this:

$ time npm run build

> cra-default-2@0.1.0 build /path/to/my/project
> react-scripts build

Creating an optimized production build...
Compiled successfully.

File sizes after gzip:

  36.81 KB  build/static/js/2.f885ce20.chunk.js
  762 B     build/static/js/runtime~main.a8a9905a.js
  550 B     build/static/js/main.0748b6c2.chunk.js
  539 B     build/static/css/main.8e316ad3.chunk.css

The project was built assuming it is hosted at the server root.
You can control this with the homepage field in your package.json.
For example, add this to build it for GitHub Pages:

  "homepage" : "http://myname.github.io/myapp",

The build folder is ready to be deployed.
You may serve it with a static server:

  npm install -g serve
  serve -s build

Find out more about deployment here:

  https://bit.ly/CRA-deploy


real	0m6.182s
user	0m10.188s
sys	0m0.524s

Actual Behavior

The command runs, but never finishes until manually killed. A few seconds into its run, it prints this message:

$ time npm run build

> cra-default-2@0.1.0 build /code/cra-project
> react-scripts build

Creating an optimized production build...
(node:29773) UnhandledPromiseRejectionWarning: Error: Debug Failure. Diagnostic emitted without context
    at throwDiagnostic (/code/cra-project/node_modules/typescript/lib/typescript.js:80390:61)
    at handleSymbolAccessibilityError (/code/cra-project/node_modules/typescript/lib/typescript.js:80461:33)
    at Object.trackSymbol (/code/cra-project/node_modules/typescript/lib/typescript.js:80480:13)
    at lookupSymbolChain (/code/cra-project/node_modules/typescript/lib/typescript.js:34535:33)
    at symbolToTypeNode (/code/cra-project/node_modules/typescript/lib/typescript.js:34687:29)
    at typeToTypeNodeHelper (/code/cra-project/node_modules/typescript/lib/typescript.js:33966:27)
    at addPropertyToElementList (/code/cra-project/node_modules/typescript/lib/typescript.js:34352:59)
    at createTypeNodesFromResolvedType (/code/cra-project/node_modules/typescript/lib/typescript.js:34302:25)
    at createTypeNodeFromObjectType (/code/cra-project/node_modules/typescript/lib/typescript.js:34135:35)
    at createAnonymousTypeNode (/code/cra-project/node_modules/typescript/lib/typescript.js:34087:42)
(node:29773) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:29773) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Reproducible Demo

https://github.com/agwells/create-react-app-bug-example

// File from step 2 of reproduction steps
interface NotExportedInterface {}

export function exportedFunction(): NotExportedInterface {
  return {};
}

// File from step 3 of reproduction steps
import { exportedFunction } from './myfunction';

export function MyComponent() {
  return null;
}
MyComponent.defaultProps = {
  myProp: exportedFunction(),
};

[agwells]

With @johnnyreilly 's help, I’ve determined it’s probably an underlying TypeScript bug. Specifically, this one: https://github.com/Microsoft/TypeScript/issues/29672

So I’ll close this issue then. 😃

[johnnyreilly]

No I haven’t - I’ve asked @agwells to try seeing if he can reproduce it outside of create-react-app:

https://github.com/Realytics/fork-ts-checker-webpack-plugin/issues/234#issuecomment-476988479

I’m going to try and help @agwells investigate it if he’s game.