fix: add fallback books when Google API returns 429

Author: adxdits

projects/ngrx-devtool-demo/src/app/book-list/book.service.ts

@@ -1,10 +1,18 @@
 import { HttpClient } from '@angular/common/http';
 import { inject, Injectable } from '@angular/core';
 
-import { Observable } from 'rxjs';
-import { map } from 'rxjs/operators';
+import { Observable, of } from 'rxjs';
+import { catchError, map } from 'rxjs/operators';
 import { Book } from './book.model';
 
+const FALLBACK_BOOKS: Book[] = [
+  { id: '1', volumeInfo: { title: 'Awakenings', authors: ['Oliver Sacks'] } },
+  { id: '2', volumeInfo: { title: 'The Man Who Mistook His Wife for a Hat', authors: ['Oliver Sacks'] } },
+  { id: '3', volumeInfo: { title: 'An Anthropologist on Mars', authors: ['Oliver Sacks'] } },
+  { id: '4', volumeInfo: { title: 'Musicophilia', authors: ['Oliver Sacks'] } },
+  { id: '5', volumeInfo: { title: 'The Island of the Colourblind', authors: ['Oliver Sacks'] } },
+];
+
 @Injectable({ providedIn: 'root' })
 export class GoogleBooksService {
   private readonly http = inject(HttpClient);
@@ -14,6 +22,9 @@ export class GoogleBooksService {
       .get<{ items: Book[] }>(
         'https://www.googleapis.com/books/v1/volumes?maxResults=5&orderBy=relevance&q=oliver%20sacks'
       )
-      .pipe(map((books) => books.items || []));
+      .pipe(
+        map((books) => books.items || []),
+        catchError(() => of(FALLBACK_BOOKS))
+      );
   }
 }