Inject() must be called from an injection context such as a constructor in AngularFirestoreDoc after upgrading to Angular v19

I recently upgraded all dependencies to Angular v19 (from v18). I was previously on Angular v18 where everything worked fine. However, now, my whole console is spammed with the following error:

```
ERROR RuntimeError: NG0203: inject() must be called from an injection context such as a constructor, a factory function, a field initializer, or a function used with `runInInjectionContext`. Find more at https://angular.dev/errors/NG0203
at injectInjectorOnly (core.mjs:1104:11)
at ɵɵinject (core.mjs:1114:40)
at inject (core.mjs:1199:10)
at (angular-fire-compat-firestore.mjs:93:14)
at new AngularFirestoreDocument (angular-fire-compat-firestore.mjs:98:3)
at _AngularFirestore.doc (angular-fire-compat-firestore.mjs:621:12)
at auth.service.ts:38:14
at switchMap.js:16:17
at OperatorSubscriber2._this._next (OperatorSubscriber.js:14:9)
at Subscriber2.next (Subscriber.js:32:12)
```

However, my auth service at line 38:14 only has the following code:
``.doc(`users/${user.uid}`)``

The whole constructor looks like this (it is a angular service class)
```@Injectable({
providedIn: 'root',
})
export class AuthService {
isLoggedIn$: Observable;
/** User data of database */
user$: Observable;
userRoles$: Observable;
userId: string | undefined = undefined;
username: string | undefined = undefined;

constructor(
readonly firestore: AngularFirestore,
readonly fireAuth: AngularFireAuth,
readonly router: Router,
) {
this.user$ = this.fireAuth.authState.pipe(
switchMap((user) => {
if (user) {
this.userId = user.uid;
return this.firestore
.doc(`users/${user.uid}`)
.valueChanges()
.pipe(
map((userData) => {
if (userData) {
this.username = userData.username; // Assign username
}
return userData;
}),
);
} else {
this.userId = undefined;
this.username = undefined;
return new Observable((observer) => observer.next(null));
}
}),
);
```

But I dont really know, why it does not work anymore in angular 19.

My package dependencies:
```
"dependencies": {
"@angular/animations": "^19.1.5",
"@angular/cdk": "^19.1.3",
"@angular/common": "^19.1.5",
"@angular/compiler": "^19.1.5",
"@angular/core": "^19.1.5",
"@angular/fire": "^19.0.0",
"@angular/forms": "^19.1.5",
"@angular/material": "^19.1.3",
"@angular/platform-browser": "^19.1.5",
"@angular/platform-browser-dynamic": "^19.1.5",
"@angular/router": "^19.1.5",
"@fortawesome/angular-fontawesome": "^1.0.0",
"@fortawesome/free-brands-svg-icons": "^6.7.1",
"@fortawesome/free-regular-svg-icons": "^6.7.1",
"@fortawesome/free-solid-svg-icons": "^6.7.1",
"@ng-select/ng-select": "^14.2.2",
"@ngx-translate/core": "^15.0.0",
"@ngx-translate/http-loader": "^8.0.0",
"angular-build-info": "^2.0.1",
"canvas-confetti": "^1.9.3",
"flowbite": "^2.5.2",
"ng-recaptcha-2": "^15.0.2",
"ngx-editor": "^18.0.0",
"ngx-quill": "^27.0.0",
"quill": "^2.0.3",
"quill2-emoji": "^0.1.2",
"rxjs": "~7.8.0",
"tslib": "^2.8.1",
"tw-elements": "^2.0.0",
"zone.js": "^0.15.0"
},
```

I also tried to set "preserveSymlinks": false, in angular.json however, the issue still persists.

Commencez par l'appel dans auth.service.ts à la ligne 38 et suivez-le à travers AngularFirestore.doc jusqu'à angular-fire-compat-firestore.mjs, en utilisant la stack trace NG0203 comme point d'entrée. Comparez les versions de dépendances signalées d'Angular v19 et de @angular/fire v19, et examinez la discussion de l'issue à la recherche d'une reproduction ou d'une résolution établie. C'est terminé lorsque l'erreur de contexte d'injection est expliquée et qu'un correctif de compatibilité vérifié ou une prochaine étape confirmée par un maintainer est identifié.

Rédigé par le modèle d'indexation à partir du texte de l'issue.