fix: Safe check for theme (#354)

Co-authored-by: tumms2021389 <[email protected]>

Author: tammy-a11y

projects/angular-test-app/src/app/_samples/embedded/embedded.component.ts

@@ -65,7 +65,7 @@ export class EmbeddedComponent implements OnInit, OnDestroy {
 
     const { authConfig, theme } = await getSdkConfig();
     document.body.classList.remove(...['light', 'dark']);
-    document.body.classList.add(theme);
+    document.body.classList.add(theme || 'dark');
     initializeAuthentication(authConfig);
 
     // Login if needed, without doing an initial main window redirect

projects/angular-test-app/src/app/_samples/full-portal/full-portal.component.ts

@@ -50,7 +50,7 @@ export class FullPortalComponent implements OnInit, OnDestroy {
   async ngOnInit() {
     const { theme } = await this.scservice.readSdkConfig();
     document.body.classList.remove(...['light', 'dark']);
-    document.body.classList.add(theme);
+    document.body.classList.add(theme || 'dark');
     this.initialize();
   }