Updated to angular 11

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

bookie/src/app/sales/reason/reason.component.ts

@@ -10,11 +10,11 @@ import { ReasonDatasource } from './reason-datasource';
   styleUrls: ['./reason.component.css'],
 })
 export class ReasonComponent {
-  @ViewChild('son', { static: true }) son: ElementRef;
+  @ViewChild('son', { static: true }) son?: ElementRef;
   form: FormGroup;
   dataSource: ReasonDatasource;
   title: string;
-  selected: string;
+  selected = '';
   reasons: string[];
   displayedColumns = ['reason'];