TypeError: this is undefined

[chaseWillden]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Performance issue
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question
[ ] Other... Please describe:

Current behavior

When building an app with ng build --prod and running the application in Firefox 47.0 on windows, I get an error that says: TypeError: this is undefined which points to bootstrapModuleFactory

Expected behavior

I expected the application to run like normal.

Minimal reproduction of the problem with instructions

1. Build an angular 6 app using ng build --prod
2. Run the application on windows firefox 47.0

What is the motivation / use case for changing the behavior?

Browser support

Environment

Angular version: 6.1.x


Browser:
- [ ] Chrome (desktop) version XX
- [ ] Chrome (Android) version XX
- [ ] Chrome (iOS) version XX
- [x] Firefox version 47
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [ ] IE version XX
- [ ] Edge version XX
 
For Tooling issues:
- Node version: v8.11.2  
- Platform: Mac  

Others:

[JoostK]

Could you provide a reproduction for this issue, otherwise it can't be analyzed. You may want to use Stackblitz and share the link here.

[josephliccini]

It won't reproduce on Stackblitz because it's only for production builds.

We have a thread here: angular/angular-cli#9340

It's due to some FF 45-50 incompatibilities with UglifyES.

If you follow the workarounds to downgrade your UglifyJsWebpackPlugin to 1.1.5 it goes away.

Our site caters to a lot of businesses who are stuck with older Firefox ESR releases due to investments in Firefox add-ons, so the downgrade fixed it for us, but a long term fix from Angular will probably be a minifier change. I'm not sure when that will land..

[IgorMinar]

I'm not sure if there is much we can do right now as explained in angular/angular-cli#9340 (comment)

In addition to Filipe's comment, another suggestion would be that since affecting only FF I suggest filing an issue against Firefox. Sorry.

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