Can't figure out what it telling me "Unexpected value 'undefined' declared by the module 'AppModule"

Question

I made a website with Angular and I imported one new module the about us and once I did that it giving me an error I already added the login,register and messages I dont know what I did different

app.module.ts

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

import { RouterModule } from '@angular/router';
import { AppComponent } from './app.component';
import { HttpClientModule } from '@angular/common/http';
import { ApiService } from './api.service';
import {MatButtonModule, MatToolbarModule, MatInputModule} from    '@angular/material';


import {BrowserAnimationsModule, NoopAnimationsModule} from     '@angular/platform-browser/animations';
 import {FormsModule, ReactiveFormsModule} from '@angular/forms';
 import {MatListModule} from '@angular/material/list';
 import { RegisterComponent } from './register/register.component';
 import { LoginComponent } from './login/login.component';
 import { MessageComponent } from './messages/message.component';
 import { AboutusComponent } from './aboutus/aboutus.component';
 @NgModule({
  declarations: [
  AppComponent, MessageComponent, RegisterComponent,     LoginComponent,AboutusComponent
   ],
   imports: [
    BrowserModule, HttpClientModule, FormsModule,     ReactiveFormsModule, MatButtonModule, MatInputModule, MatToolbarModule,     BrowserAnimationsModule,
    NoopAnimationsModule, MatListModule, RouterModule.forRoot(
    [{path: 'register', component: RegisterComponent},
    {path: 'login', component: LoginComponent},
    {path: 'messages', component: MessageComponent} 
  ]
)
],
 providers: [ApiService],
 bootstrap: [AppComponent]
  })
export class AppModule { }

aboutus.componenet.ts

import { Component, OnInit } from '@angular/core';

@Component({
selector: 'aboutus',
templateUrl: './aboutus.component.html'
 })
  export class AboutusComponent{
  constructor(){ }

  ngOnInit(){
  }
}

Answer 1

Your AboutusComponent should implement OnInit

export class AboutusComponent implements OnInit {

or remove ngOnInit()