fix(cdn): makes CDN_CONFIG optional

this helps especially with testing

libs/utils/cdn/src/lib/cdn.service.spec.ts

@@ -251,3 +251,21 @@ describe('CdnService', () => {
     });
   });
 });
+
+describe('CdnService with no CDN_CONFIG', () => {
+  let service: CdnService;
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      providers: [CdnService]
+    });
+    service = TestBed.get(CdnService);
+  });
+
+  it('should create', () => {
+    expect(service).toBeDefined();
+  });
+
+  it('should use default baseUrl', () => {
+    expect(service.uri('test')).toBe('https://static.apps.psu.edu/test');
+  });
+});

libs/utils/cdn/src/lib/cdn.service.ts

@@ -15,7 +15,9 @@ import { CdnUri } from './cdn.model';
 @Injectable({ providedIn: 'root' })
 export class CdnService {
   constructor(
-    @Inject(CDN_CONFIG) private config: CdnConfig,
+    @Optional()
+    @Inject(CDN_CONFIG)
+    private config: CdnConfig,
     @Optional()
     @Inject(CDN_RESOURCE_CONFIG)
     private resourceConfig: CdnResourceConfig[],
@@ -25,7 +27,10 @@ export class CdnService {
   ) {}
 
   private get cdnUrl(): string {
-    let url = this.config.baseUrl || 'https://static.apps.psu.edu';
+    let url = 'https://static.apps.psu.edu';
+    if (this.config && this.config.baseUrl) {
+      url = this.config.baseUrl;
+    }
     if (url && url.lastIndexOf('/') === url.length - 1) {
       url = url.substr(0, url.length - 1);
     }