This post shows you how to solve the problem You seem to not be depending on "@angular/core" and/or "rxjs". This is an error in Angular 7.

You seem to not be depending on "@angular/core" and/or "rxjs". This is an error.

To solve the problem you should approach the following way.

npm link

Next, build your angular project as the following command.

ng serve

I hope so you can solve the problem.