Angular test cannot access Service before initialization

Question

I cannot make tests start, because they fail at the very beginning with error

Chrome 83.0.4103.61 (Linux x86_64) ERROR
  An error was thrown in afterAll
  Uncaught ReferenceError: Cannot access 'SomeService' before initialization
  ReferenceError: Cannot access 'SomeService' before initialization

... stack trace

The thing is:

a) It's a singleton service and providedIn: 'root'

b) Stack trace points to nowhere (it even includes test files which are totally commented out so there is no single line of code.

c) Other tests don't start because of that

d) I can't start disabling tests to find the starting point due to their amount.

How do I find where an error could happen and what could cause this? Can it be connected to updating Karma, Jasmine and spec reporters to the latest versions of their packages? I'm working with Angular 9

Answer 1

It appears that it's due to project's "age". It was started with Angular 6. According to this comment emitDecoratorMetadata in the config is the cause. After deleting this everything works fine...