TypeError: Cannot read property '__esModule' of undefined when /* webpackPrefetch: true */

[agawley]

🐛 Bug Report

I am using serverless to deploy a React app. When I use loadable for code splitting everything is fine until I try to prefretch resources. Adding /* webpackPrefetch: true */ causes a server side crash on importing my < App >

TypeError: Cannot read property '__esModule' of undefined
    at /Users/alexgawley/code/serverless/tmp/loadable-repro/.webpack/service/src/servers/static.js:29310:34
    at Object.<anonymous> (/Users/alexgawley/code/serverless/tmp/loadable-repro/.webpack/service/src/servers/static.js:29312:12)
    at Module._compile (internal/modules/cjs/loader.js:999:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1027:10)
    at Module.load (internal/modules/cjs/loader.js:863:32)
    at Function.Module._load (internal/modules/cjs/loader.js:708:14)
    at Module.require (internal/modules/cjs/loader.js:887:19)
    at require (internal/modules/cjs/helpers.js:74:18)
    at /Users/alexgawley/code/serverless/tmp/loadable-repro/node_modules/serverless-offline/dist/lambda/handler-runner/in-process-runner/InProcessRunner.js:157:133
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async InProcessRunner.run (/Users/alexgawley/code/serverless/tmp/loadable-repro/node_modules/serverless-offline/dist/lambda/handler-runner/in-process-runner/InProcessRunner.js:157:9)

To Reproduce

Steps to reproduce the behavior:

git clone https://github.com/agawley/loadable-repro
npm i
npm run offline

load http://localhost:3000

Expected behavior

The page should load with a 'show/hide' link which reveals the lazy-loaded component SomeText. If you remove the /* webpackPrefetch: true */ comment from app.js you get the expected behaviour (but no prefetching!)

Link to repl or repo (highly encouraged)

https://github.com/agawley/loadable-repro

Please provide a minimal repository on GitHub.

https://github.com/agawley/loadable-repro

Issues without a reproduction link are likely to stall.

Run npx envinfo --system --binaries --npmPackages @loadable/component,@loadable/server,@loadable/webpack-plugin,@loadable/babel-plugin --markdown --clipboard

Paste the results here:

## System:
 - OS: macOS 10.15.7
 - CPU: (12) x64 Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
 - Memory: 834.46 MB / 16.00 GB
 - Shell: 5.7.1 - /bin/zsh
## Binaries:
 - Node: 12.22.1 - ~/.nvm/versions/node/v12.22.1/bin/node
 - Yarn: 1.22.10 - /usr/local/bin/yarn
 - npm: 7.13.0 - ~/.nvm/versions/node/v12.22.1/bin/npm
## npmPackages:
 - @loadable/babel-plugin: ^5.13.2 => 5.13.2 
 - @loadable/component: ^5.15.0 => 5.15.0 
 - @loadable/server: ^5.15.0 => 5.15.0 
 - @loadable/webpack-plugin: ^5.15.0 => 5.15.0 

[open-collective-bot]

Hey @agawley 👋,
Thank you for opening an issue. We'll get back to you as soon as we can.
Please, consider supporting us on Open Collective. We give a special attention to issues opened by backers.
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[agawley]

Hiya. Does anyone have any ideas on this? Another couple of days of debugging hasn't helped. I'm pretty sure this is going to be something whacky to do with my having two different webpack configs, but I can't for the life of me figure out what. Thanks!

[theKashey]

I've also experienced some problems with prefetch, to the level that I cannot use them, but not even close to your case.

[agawley]

Got an answer from webpack. It's a bug in webpack (webpack/webpack#12993). PR is here (webpack/webpack#13431)