Loading google maps api with APP_INITIALIZER provider in Angular

app.module.ts

export function appConfigInit(configService: AppConfigService,
                              googleMapService: GoogleMapsService, logging: LoggingService) {
    // Load the configuration and init google api if maps should be used
    return () => {
        return new Promise((resolve) => {
            configService.load().then(() => {
                if (configService.useMap) {
                    logging.logInfo('Use map');
                    googleMapService.load(configService.googleAPIKey).then(() => {
                        resolve();
                    });
                } else {
                    logging.logInfo('no map');
                    resolve();
                }
            });
        });
    };
}

@NgModule({
    declarations: [
        AppComponent,
        LocationsListComponent,
        AppBarComponent,
        LocationDetailsComponent,
        MapComponent,
        NumberRangeValidator
    ],
    providers: [
        AppConfigService,
        GoogleMapsService,
        LoggingService,
        {
            provide: APP_INITIALIZER,
            useFactory: appConfigInit,
            multi: true,
            deps: [AppConfigService, GoogleMapsService, LoggingService]
        },