Updated to angular 11

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

bookie/src/app/product-sale-report/product-sale-report.ts

@@ -3,5 +3,12 @@ import { ProductSaleReportItem } from './product-sale-report-item';
 export class ProductSaleReport {
   startDate: string;
   finishDate: string;
-  amounts?: ProductSaleReportItem[];
+  amounts: ProductSaleReportItem[];
+
+  public constructor(init?: Partial<ProductSaleReport>) {
+    this.startDate = '';
+    this.finishDate = '';
+    this.amounts = [];
+    Object.assign(this, init);
+  }
 }