fix: Ensure ShortInformation and FullInformation default to empty string in Create and Update Discount Product commands

src/BackOffice.BFF.Application/DiscountProductCQ/Commands/CreateDiscountProduct/CreateDiscountProductCommandHandler.cs

@@ -17,8 +17,8 @@ public class CreateDiscountProductCommandHandler : IRequestHandler<CreateDiscoun
         var createRequest = new CreateDiscountProductRequest
         {
             Title = request.Title,
-            ShortInfomation = request.ShortInformation,
-            FullInformation = request.FullInformation,
+            ShortInfomation = request.ShortInformation ?? string.Empty,
+            FullInformation = request.FullInformation ?? string.Empty,
             Price = request.Price,
             MaxDiscountPercent = request.MaxDiscountPercent,
             SortOrder = request.SortOrder,

src/BackOffice.BFF.Application/DiscountProductCQ/Commands/UpdateDiscountProduct/UpdateDiscountProductCommandHandler.cs

@@ -18,8 +18,8 @@ public class UpdateDiscountProductCommandHandler : IRequestHandler<UpdateDiscoun
         {
             ProductId = request.ProductId,
             Title = request.Title,
-            ShortInfomation = request.ShortInformation,
-            FullInformation = request.FullInformation,
+            ShortInfomation = request.ShortInformation ?? string.Empty,
+            FullInformation = request.FullInformation ?? string.Empty,
             Price = request.Price,
             MaxDiscountPercent = request.MaxDiscountPercent,
             SortOrder = request.SortOrder,