NullInjectorError: R3InjectorError(AppModule)[AuthServiceService -> HttpClient -> HttpClient -> HttpClient]: code example

Example 1: angular No provider for HttpClient

// open the root app.module.ts,
import { HttpClientModule } from '@angular/common/http';

// add it to the @NgModule.imports array.
imports:[HttpClientModule,  ]

Example 2: NullInjectorError: No provider for HttpClient!

@NgModule({
...
imports:[ HttpClientModule ]
...
})