Function calls are not supported in decorators but 'InjectionToken' was called in 'AbTestsModule'

[markpesantes]

Currently running Angular 7.2.7 and CLI version 7.3.4

I get the following error when including this in my app module root upon attempting to run the application:

ERROR in Error during template compile of 'AppModule'
  Function calls are not supported in decorators but 'InjectionToken' was called in 'AbTestsModule'
    'AbTestsModule' references 'CONFIG'
      'CONFIG' calls 'InjectionToken' at ../angular-ab-tests/angular-ab-tests.ts(4,27).

This is followed up by repeat ambient errors like:

node_modules/angular-ab-tests/node_modules/@angular/core/core.d.ts(1088,18): error TS1086: An accessor cannot be declared in an ambient context.

[raphzandrade]

Also having this problem :(

EDIT:
the versions i am using:
"@angular/cli": "~8.2.0",
"@angular/core": "^8.2.13",

[markpesantes]

@adrdilauro please let me know if you need more specific information about my setup