[BUG]: Multiple exports break hot reloading

Created by: eccentric-j

Describe the bug

When a component file contains more than one export, CRA cannot hot-reload it.

Did you try recovering your dependencies?

Yes, experienced it on our work repo. Reproduced it in another person's test reproduction repo who ran into it, and then moments ago created a brand new create-react-app app and reproduced the issue again.

Which terms did you search for in User Guide?

Multiple exports found https://create-react-app.dev/docs/importing-a-component/#dangerbuttonjs which doesn't mention anything about an issue like this
Hot Module Replacement
Hot Reloading
Fast Reload
Reloading

Environment

>  npx create-react-app --info

Environment Info:

  current version of create-react-app: 4.0.3
  running from /Users/j/.npm/_npx/c67e74de0542c87c/node_modules/create-react-app

  System:
    OS: macOS 11.2.3
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
  Binaries:
    Node: 15.11.0 - /usr/local/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 7.6.0 - /usr/local/bin/npm
  Browsers:
    Chrome: Not Found
    Edge: Not Found
    Firefox: Not Found
    Safari: 14.0.3
  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

Run npx create-react-app cra-reload-repro
Open App.js and add this to the very bottom export const x = 5. Doesn't seem to matter what is exported.
Run yarn start
View in browser
Edit App.js and change some text, maybe a single word
Save changes to App.js

Expected behavior

The module is sent via WebSocket to the browser and then the update is applied so the text changes on-screen.

Actual behavior

The module is sent via WebSocket (confirmed in network tab of inspector), but the update is not applied. The text does not change on-screen.

Reproducible demo

https://github.com/eccentric-j/cra-reload-repro

Clone the repo
Run yarn start
Open page in browser
Change some text in App.js
Save App.js

Notes

If I should report this to another package or github repo, please point the way!