angular: Signals: Writing to signals is not allowed in a `computed`

Which @angular/* package(s) are the source of the bug?

core

Is this a regression?

No

Description

I believe there is a bug in creating computed signal from method returning observable:

 constructor(private injector: Injector) {}
  userId: Signal<string> = signal('userA');
  roles = computed(() =>
    toSignal(getRoles(this.userId()), { injector: this.injector })()
  );

//this could be api service sending  http request
const getRoles = (userId: string) => {
  return userId === 'userA' ? of([1, 2, 3]) : of([1]);
};

This code throws runtime console error Error: NG0600: Writing to signals is not allowed in a computedor aneffectby default. UseallowSignalWritesin theCreateEffectOptions to enable this inside effects.

However, that does not seem to be case of writing to signal. I read signal userId and I convert observable into signal via toSignal() method. No writing anywhere. Am I wrong?

Stackblitz here

Please provide a link to a minimal reproduction of the bug

https://stackblitz.com/edit/angular-admqds?file=src/main.ts

Please provide the exception or error you saw

Error: NG0600: Writing to signals is not allowed in a `computed` or an `effect` by default. Use `allowSignalWrites` in the `CreateEffectOptions` to enable this inside effects.

Please provide the environment you discovered this bug in (run ng version)

Angular 16
Nodejs 18.10

Anything else?

No response