Fix: Cancel bill printing if discount dialog is cancelled.

bookie/src/app/sales/home/sales-home.component.ts

@@ -149,6 +149,8 @@ export class SalesHomeComponent {
         tap((result: boolean | { id: string; name: string; discount: number }[]) => {
           if (result) {
             this.bs.discount(result as { id: string; name: string; discount: number }[]);
+          } else {
+            throw new Error('Cancelled');
           }
         }),
         switchMap(() => this.billTypeDialog()),