Not compile code of angular 5 in prod mode.

Question

Hi all,

 

I am using this code

import { NgModule, ModuleWithProviders } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { MainModule } from './main/main.module';
import { AuthModule } from './auth/auth.module';
const routes: Routes = [
{path: '', redirectTo: 'auth', pathMatch: 'full'},
{path: 'login' , redirectTo: 'auth' , pathMatch: 'full'},
{path: 'auth', loadChildren: () => AuthModule }
];
@NgModule({
imports: [RouterModule.forRoot(routes)],
exports: [RouterModule],
})
export class AppRoutingModule { }

It works with ng build but did not work with prod mode  'ng build --prod'