Build and trying to run very basing angular project which is just giving message "Server is up and running" but not loading html page

I am new with Angular Js and trying to build very basic simple navigation menu listing project. Initially I was able to built and run angular project and view index.html page in browser. But after installing bootstrap npm package i started to face weird issue. on build project I can see project build successfully including index.html and assets. -

After that on running project getting below screen in browser -

Below is my index.html

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Angular Test</title>
  <base href="/">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" type="image/x-icon" href="favicon.ico">
</head>
<body>
  <app-root>test</app-root>
</body>
</html>

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import {NavMenuDashboard} from './top-menu-bar/top-bar.component';
 
@NgModule({
  declarations: [
    AppComponent,
    NavMenuDashboard,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

I am just trying to build simple navigation menu link display project using angularjs, typescript and bootstrap.