set 404 content

src/app/header/header.component.ts

@@ -8,8 +8,10 @@ import {HttpClient} from "@angular/common/http";
 })
 export class HeaderComponent implements OnInit {
 
-  constructor(private httpClient: HttpClient) { }
-  title = null;
+  constructor(private httpClient: HttpClient) {
+  }
+
+  title: string | undefined;
 
   ngOnInit(): void {
     let location = document.documentURI.replace(document.baseURI, '');
@@ -20,7 +22,7 @@ export class HeaderComponent implements OnInit {
         this.title = data.title;
         document.title = data.title + ' - Jonas Leder';
       } else {
-        "404 - Page not found";
+        this.title = "404 - Page not found";
       }
 
     });