Refactored customer discount and choose discount. They were using the same schema unnecessarily which was leading to confusion.

bookie/src/app/core/customer-discount.ts

@@ -1,12 +1,14 @@
 export class CustomerDiscount {
   id: string;
   name: string;
-  discount: number | null;
+  discount: number;
+  limit: number;
 
   public constructor(init?: Partial<CustomerDiscount>) {
     this.id = '';
     this.name = '';
-    this.discount = null;
+    this.discount = 0;
+    this.limit = 1;
     Object.assign(this, init);
   }
 }