How can I access to the _angularFireAuth.auth.currentUser.email inside a person.service.ts?

I’m writing an ionic angular application with login/password security using Firebase.
I’ve no issue to get the value back of _angularFireAuth.auth.currentUser.email inside any pages except from a person.service.ts that is defined as a service.
Could you please help me to solve that.

Here is my person.service.ts:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';
import InvoicesList from './subtypes';
import { AngularFireAuth } from '@angular/fire/auth';
import { auth } from 'firebase';

@Injectable({
  providedIn: 'root'
})
export class PersonService {

  constructor(private _httpClient: HttpClient,
    private _angularFireAuth2: AngularFireAuth ) { }

  getAllNonSignedInvoicesForOne(personemail: string): Observable<InvoicesList[]>{
    console.log(this._angularFireAuth2.auth.currentUser.email);
    return this._httpClient.get<InvoicesList[]>(APIAllNonSignedInvForOne+"&email=" + personemail);
  }
}

const APIAllNonSignedInvForOne = "http://www.XXXX.be/v/ebills/call.php?query=allinvoices&signed=N";

The console is complaining with:

AppComponent_Host.ngfactory.js? [sm]:1 ERROR TypeError: Cannot read property 'email' of null
    at PersonService.getAllNonSignedInvoicesForOne (person.service.ts:43)
    at new AppComponent (app.component.ts:121)
    at createClass (core.js:31998)
    at createDirectiveInstance (core.js:31807)
    at createViewNodes (core.js:44210)
    at createRootView (core.js:44082)
    at callWithDebugContext (core.js:45632)
    at Object.debugCreateRootView [as createRootView] (core.js:44848)
    at ComponentFactory_.create (core.js:30788)
    at ComponentFactoryBoundToModule.create (core.js:25731)

But if I write at the same place console.log(this._angularFireAuth2.auth);
I see all this log where I can find my mail… Very strange… Can you please help me?

Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(4), …}
B: null
I: []
INTERNAL: {delete: ƒ, logFramework: ƒ}
J: [ƒ]
Ja: ƒ ()
O: Array(0)
length: 0
__proto__: Array(0)
P: null
Sb: Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(0), …}
Tb: B {a: 2, i: dl, c: null, b: null, f: null, …}
Ub: ƒ ()
Vb: ƒ ()
W: "Ot93XXXXXXXXXXmyqo1"
Xa: null
Y: B {a: 2, i: undefined, c: null, b: null, f: null, …}
Z: null
a: dl {i: {…}, v: 0, B: "eXXXfirebaseapp.com", u: "XXXXXXXXXXXXX", m: "[DEFAULT]", …}
app: FirebaseAppImpl {firebase_: {…}, isDeleted_: false, name_: "[DEFAULT]", automaticDataCollectionEnabled_: false, options_: {…}, …}
b: oi {c: "AIXXXXXXXXXXw", l: "https://securetoken.googleapis.com/v1/token", u: Qe, g: {…}, h: "https://www.googleapis.com/identitytoolkit/v3/relyingparty/", …}
currentUser: Q
I: []
J: true
O: [ƒ]
P: []
Sb: Q {I: Array(0), l: "XXXXXXXXXXXXXXXw", m: "[DEFAULT]", o: "eXXXXXXXXfirebaseapp.com", a: oi, …}
W: ƒ ()
Xa: null
Y: Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(0), …}
Z: Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(0), …}
a: oi {c: "XXXXXw", l: "https://securetoken.googleapis.com/v1/token", u: Qe, g: {…}, h: "https://www.googleapis.com/identitytoolkit/v3/relyingparty/", …}
b: Il {f: oi, a: "AXX", b: "eXXXXrQ", c: XXX
da: zm {a: "AXXX:[DEFAULT]", b: qk}
displayName: null
email: "XXXXXXXXXvincent@gmail.com"
emailVerified: false
ga: null
h: null
i: dl {i: {…}, v: 0, B: "XXXX.com", u: "XXXXXX", m: "[DEFAULT]", …}
isAnonymous: false
l: "XXXXXX"
la: undefined
m: "[DEFAULT]"
ma: "Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(4), …}
B: null
I: []
INTERNAL: {delete: ƒ, logFramework: ƒ}
J: [ƒ]
Ja: ƒ ()
O: Array(0)
length: 0
__proto__: Array(0)
P: null
Sb: Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(0), …}
Tb: B {a: 2, i: dl, c: null, b: null, f: null, …}
Ub: ƒ ()
Vb: ƒ ()
W: "xxxxxxxxxx"
Xa: null
Y: B {a: 2, i: undefined, c: null, b: null, f: null, …}
Z: null
a: dl {i: {…}, v: 0, B: "xxxxxxeapp.com", u: "xxxxx", m: "[DEFAULT]", …}
app: FirebaseAppImpl {firebase_: {…}, isDeleted_: false, name_: "[DEFAULT]", automaticDataCollectionEnabled_: false, options_: {…}, …}
b: oi {c: "xxxxx", l: "https://securetoken.googleapis.com/v1/token", u: Qe, g: {…}, h: "https://www.googleapis.com/identitytoolkit/v3/relyingparty/", …}
currentUser: Q
I: []
J: true
O: [ƒ]
P: []
Sb: Q {I: Array(0), l: "AIxxxxxxxxw", m: "[DEFAULT]", o: "xxxxxxxx.firebaseapp.com", a: oi, …}
W: ƒ ()
Xa: null
Y: Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(0), …}
Z: Lm {l: false, settings: Bl, app: FirebaseAppImpl, b: oi, O: Array(0), …}
a: oi {c: "xxxxxxxxx", l: "https://securetoken.googleapis.com/v1/token", u: Qe, g: {…}, h: "https://www.googleapis.com/identitytoolkit/v3/relyingparty/", …}
b: Il {f: oi, a: "AxxxxA", b: "exxxxxxx", c: xxxxxx
da: zm {a: "xxxxxx:[DEFAULT]", b: qk}
displayName: null
email: "XXXXXXXXXXvincent@gmail.com"
emailVerified: false
ga: null
h: null
i: dl {i: {…}, v: 0, B: "exxxxxxx.firebaseapp.com", u: "Axxxxx", m: "[DEFAULT]", …}
isAnonymous: false
l: xx9w"
la: undefined
m: "[DEFAULT]"
ma: "xxxxxxx
metadata: Nl {a: xxx b: xx lastSignInTime: "Tue, 08 Sep 2020 13:19:19 GMT", creationTime: "Wed, 19 Feb 2020 13:36:56 GMT"}
o: "ebill-fa229.firebaseapp.com"
phoneNumber: null
photoURL: null
providerData: [{…}]
refreshToken: "Axxxxxxxx
tenantId: null
u: Rc {src: Q, a: {…}, b: 3}
uid: xxxxxxxxx
va: false
w: Fl {c: 30000, f: 960000, h: ƒ, i: ƒ, g: ƒ, …}
wa: ƒ (e)
xa: ƒ (e)
_lat: "xxxxxxx
__proto__: G
ga: true
h: Bm {a: "xxxxxxxxxx:[DEFAULT]", b: qk, c: {…}, f: B}
i: B {a: 2, i: undefined, c: null, b: null, f: null, …}
l: false
la: undefined
languageCode: (...)
m: [ƒ]
ma: ƒ ()
o: 0
settings: Bl {vb: false}
tenantId: (...)
u: Rc {src: Lm, a: {…}, b: 2}
ub: ƒ ()
va: false
w: zm {a: "Axxxxxxxxxw:[DEFAULT]", b: qk}
wa: ƒ ()
xa: ƒ ()
lc: (...)
ti: (...)
get lc: ƒ ()
set lc: ƒ (b)
get ti: ƒ ()
set ti: ƒ (b)
__proto__: xxxxxxxxxxx
metadata: Nl {a: xxxxx  b: xxxxxxx  lastSignInTime: "Tue, 08 Sep 2020 13:19:19 GMT", creationTime: "Wed, 19 Feb 2020 13:36:56 GMT"}
o: "exxx.firebaseapp.com"
phoneNumber: null
photoURL: null
providerData: [{…}]
refreshToken: "Axxxxxxx
tenantId: null
u: Rc {src: Q, a: {…}, b: 3}
uid: "xxxxxx1"
va: false
w: Fl {c: 30000, f: 960000, h: ƒ, i: ƒ, g: ƒ, …}
wa: ƒ (e)
xa: ƒ (e)
_lat: "xxxxxxx
__proto__: G
ga: true
h: Bm {a: "xxxxxxxxxxx:[DEFAULT]", b: qk, c: {…}, f: B}
i: B {a: 2, i: undefined, c: null, b: null, f: null, …}
l: false
la: undefined
languageCode: (...)
m: [ƒ]
ma: ƒ ()
o: 0
settings: Bl {vb: false}
tenantId: (...)
u: Rc {src: Lm, a: {…}, b: 2}
ub: ƒ ()
va: false
w: zm {a: "xxxxxxxx[DEFAULT]", b: qk}
wa: ƒ ()
xa: ƒ ()
lc: (...)
ti: (...)
get lc: ƒ ()
set lc: ƒ (b)
get ti: ƒ ()
set ti: ƒ (b)
__proto__: G