Modify components to use behaviour subject.

src/app/app.module.ts

@@ -8,6 +8,7 @@ import {SharedModule} from './shared/shared.module';
 import {HttpClientModule} from '@angular/common/http';
 import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
 import {MatTableModule} from '@angular/material/table';
+import {MockBackendProvider} from './_helpers';
 
 @NgModule({
   declarations: [
@@ -22,7 +23,9 @@ import {MatTableModule} from '@angular/material/table';
     BrowserAnimationsModule,
     MatTableModule
   ],
-  providers: [],
+  providers: [
+    MockBackendProvider
+  ],
   bootstrap: [AppComponent]
 })
 export class AppModule { }