Strict done!!

overlord/src/app/balance-sheet/balance-sheet.ts

@@ -4,4 +4,10 @@ export class BalanceSheet {
   date: string;
   body: BalanceSheetItem[];
   footer?: BalanceSheetItem;
+
+  public constructor(init?: Partial<BalanceSheet>) {
+    this.date = '';
+    this.body = [];
+    Object.assign(this, init);
+  }
 }