Is this a bug report?

(write your answer here)

Yes.

Though is related to fixed webpack version of 3.8.1:

• Modules is missing in production mode webpack/webpack#7499
• Webpack 4.10.0 destroys production build webpack/webpack#7425

And we use react-app-rewired, with typescripts, which uses your package und your nailed webpack version.

Can you also reproduce the problem with npm 4.x?

I use npm 5...

Which terms did you search for in User Guide?

(Write your answer here if relevant.)

Environment

1. npm ls react-scripts-ts (if you haven’t ejected):
2. node -v:
3. npm -v:
4. yarn --version (if you use Yarn):
5. npm ls react-scripts-ts (if you haven’t ejected):

Then, specify:

1. Operating system:
2. Browser and version (if relevant):

Steps to Reproduce

(Write your steps here:)

We have a reproduction repo:

1. git clone https://github.com/martinoss/reproduce-scss-bug
2. yarn build
3. open localhost
4. Will throw:
   TypeError: Cannot read property 'call' of undefined

   o (main.9cac5c4f.js:formatted:26)
   544 (persons-list.scss:1)
   o (main.9cac5c4f.js:formatted:26)
   543 (persons-list.scss?3174:4)
   o (main.9cac5c4f.js:formatted:26)
   542 (1.56e5fc78.chunk.js:1)
   o (main.9cac5c4f.js:formatted:26)
   Promise.then (async)
   loader (routes.ts:6)
   f (main.9cac5c4f.js:formatted:6499)
   v (main.9cac5c4f.js:formatted:6566)
   n (main.9cac5c4f.js:formatted:6591)
   Ii (main.9cac5c4f.js:formatted:11110)
   da (main.9cac5c4f.js:formatted:11833)
   ha (main.9cac5c4f.js:formatted:11854)
   Ga (main.9cac5c4f.js:formatted:12109)
   Ya (main.9cac5c4f.js:formatted:12068)
   Ha (main.9cac5c4f.js:formatted:12056)
   za (main.9cac5c4f.js:formatted:12011)
   ba (main.9cac5c4f.js:formatted:11941)
   enqueueSetState (main.9cac5c4f.js:formatted:10547)
   O.setState (main.9cac5c4f.js:formatted:7392)
   t (main.9cac5c4f.js:formatted:6630)
   (anonymous) (main.9cac5c4f.js:formatted:6638)
   Promise.then (async)
   n._loadModule (main.9cac5c4f.js:formatted:6637)
   n.componentWillMount (main.9cac5c4f.js:formatted:6608)
   li (main.9cac5c4f.js:formatted:10594)
   Ii (main.9cac5c4f.js:formatted:11117)
   da (main.9cac5c4f.js:formatted:11833)
   ha (main.9cac5c4f.js:formatted:11854)
   Ga (main.9cac5c4f.js:formatted:12109)
   Ya (main.9cac5c4f.js:formatted:12068)
   Ha (main.9cac5c4f.js:formatted:12056)
   za (main.9cac5c4f.js:formatted:12011)
   ba (main.9cac5c4f.js:formatted:11941)
   ou (main.9cac5c4f.js:formatted:12498)
   au (main.9cac5c4f.js:formatted:12508)
   hu.render (main.9cac5c4f.js:formatted:12705)
   (anonymous) (main.9cac5c4f.js:formatted:12599)
   eu (main.9cac5c4f.js:formatted:12435)
   vu (main.9cac5c4f.js:formatted:12598)
   render (main.9cac5c4f.js:formatted:12755)
   (anonymous) (main.9cac5c4f.js:formatted:7334)
   o (main.9cac5c4f.js:formatted:26)
   (anonymous) (main.9cac5c4f.js:formatted:6753)
   o (main.9cac5c4f.js:formatted:26)
   (anonymous) (main.9cac5c4f.js:formatted:100)
   (anonymous) (main.9cac5c4f.js:formatted:101)

Expected Behavior

(Write what you thought would happen.)

Webpack's automatic Code-Splitting should work, containing all needed modules.

Actual Behavior

(Write what happened. Please add screenshots!)

Webpacks automatic Code-Splitting does not work, because at least one module is missing.
This is a known webpack bug, and higher versions should provide bugfixes.

Reproducible Demo

(Paste the link to an example project and exact instructions to reproduce the issue.)

https://github.com/martinoss/reproduce-scss-bug