How to inject repository in the application class using dagger (GithubBrowserSample)?

Question

I want to implement authentication in my application, so I want to get the current logged user in the application class, I am following GithubBrowserSample to develop my application, but I am very new to dagger injection and I am a little lost in how to inject my authRepository to my application class.

class App : Application(), HasActivityInjector {
    @Inject
    lateinit var dispatchingAndroidInjector: DispatchingAndroidInjector<Activity>

    override fun onCreate() {
        super.onCreate()
        if (BuildConfig.DEBUG) {
            Timber.plant(Timber.DebugTree())
        }
        AppInjector.init(this)
    }

    override fun activityInjector() = dispatchingAndroidInjector

}

I tried adding something like

@Inject 
lateinit var authRepository: AuthRepository

in the application class and in the AppModule

//I already have functions that provide everything the repository needs
@Singleton
@Provides
fun provideAuthRepository(
        appExecutors: AppExecutors,
        db: AppDatabase,
        trainersService: TrainersService,
        sessionDao: SessionDao,
        tokenInterceptor: TokenInterceptor
): AuthRepository {
    return AuthRepository(
            appExecutors,
            db,
            trainersService,
            sessionDao,
            tokenInterceptor
    )
}

but it throws Uninitialized Property Access Exception

Hope you can help me to achive this following the github sample approach.