My code base is not that old, it was written with version 7 of Angular.
When I run
ng update @angular/cli @angular/core
all that happens is updated library references, changes to some routes, a couple of ViewChild changes, and a file called browserslist is moved. I ran right through an upgrading list and got this error, so I started again and just ran this command and it immediately gives this error.
I have no ScrollbarHelper in my code. I've googled and found three posts, none very helpful. A vanilla version 7 project that is updated runs just fine. My next step will be to import my existing code a bit at a time to find out which bit causes this error to occur.