I'm using the Angular Version 11.1.1.

The command

`ng test --browsers=ChromeHeadlessCI`

is a valid one when I'm using

`@angular-builders/custom-webpack:karma`

in the `test`-section of `angular.js`.

But when I'm using

`@angular-builders/custom-webpack:browser`

in the `test`-section instead, then I get the error above when I'm testing.

Yoa are using

`@angular-builders/custom-webpack:browser`

in the `test`-section in your article instead of `...karma`. Hence testing doesn't work in your article throwing the error above.