Updated to angular 11

Now compiling with strict mode in typescript
Need to error checking now

bookie/src/app/header-footer/header-footer.component.ts

@@ -15,10 +15,10 @@ import { HeaderFooterService } from './header-footer.service';
   styleUrls: ['./header-footer.component.css'],
 })
 export class HeaderFooterComponent implements OnInit {
-  @ViewChild('section', { static: true }) sectionElement: ElementRef;
+  @ViewChild('section', { static: true }) sectionElement?: ElementRef;
   form: FormGroup;
-  list: HeaderFooter[];
-  id: string;
+  list: HeaderFooter[] = [];
+  id = '';
 
   constructor(
     private route: ActivatedRoute,
@@ -28,30 +28,29 @@ export class HeaderFooterComponent implements OnInit {
     private dialog: MatDialog,
     private ser: HeaderFooterService,
   ) {
-    this.createForm();
+    // Create form
+    this.form = this.fb.group({
+      id: '',
+      text: '',
+    });
     route.params.pipe(map((p) => p.id)).subscribe((x) => {
       this.id = x;
     });
   }
 
-  createForm() {
-    this.form = this.fb.group({
-      id: '',
-      text: '',
-    });
-  }
-
   ngOnInit() {
-    this.route.data.subscribe((data: { list: HeaderFooter[] }) => {
+    this.route.data.subscribe((value) => {
+      const data = value as { list: HeaderFooter[] };
       this.showItem(data.list);
     });
   }
 
   showItem(list: HeaderFooter[]) {
     this.list = list;
+    const val = this.list.find((v) => v.id === this.id) as HeaderFooter;
     this.form.setValue({
       id: this.id,
-      text: this.list.find((v) => v.id === this.id).text,
+      text: val.text,
     });
   }
 
@@ -70,6 +69,7 @@ export class HeaderFooterComponent implements OnInit {
   getItem(): HeaderFooter {
     const formModel = this.form.value;
     const item = this.list.find((v) => v.id === this.id);
+    if (item === undefined) return new HeaderFooter();
     item.text = formModel.text;
     return item;
   }