native-shim cannot be bundled because includes errors about custom-elements

[whyboris]

Issue resolved on the Angular CLI issue page: angular/angular-cli#7509
The solution was to bypass uglification by including the script into the angular-cli.json file instead of the polyfils.ts file.

[whyboris]

Similar problem on our setup. The app works fine locally, but when the server tries to build (Angular CLI, not explicit webpack config), in its last step:

ERROR in polyfills.f73c9a87ee1979c6555e.bundle.js from UglifyJs
Unexpected token: punc ()) [polyfills.f73c9a87ee1979c6555e.bundle.js:1633,2]

Specifically, the error occurs in:
node_modules/@webcomponents/custom-elements/src/native-shim.js:61,0]
which is simply (() => {

I created an issue with UglifyJs mishoo/UglifyJS#2287
and was told that it's not an UglifyJs issue but an Angular CLI.

I created an issue with the Angular: angular/angular-cli#7509

[bicknellr]

Hi, @whyboris, was this specifically an angular-cli issue? Anything on our end that still needs attention?

[whyboris]

In my case it was just an angular-cli issue and no work is needed from custom-elements, thank you.
I hope my link to the angular issue will help others who end up running into the same problem 👍

[bicknellr]

Thanks, glad you figured it out! I'll close this bug then.