refactor(@angular/ssr): replace incorrect check

This should be undefined and not null.

Author: alan-agius4

packages/angular/ssr/src/utils/ng.ts

@@ -109,7 +109,7 @@ export async function renderAngular(
 
     if (!routerIsProvided) {
       hasNavigationError = false;
-    } else if (lastSuccessfulNavigation?.finalUrl && initialUrl !== null) {
+    } else if (lastSuccessfulNavigation?.finalUrl && initialUrl !== undefined) {
       hasNavigationError = false;
 
       const { finalUrl } = lastSuccessfulNavigation;