hi i have error when using System.Net.Http
for inject HttpClient
i see paypalstandard plugin you use it simpel
but when i add it , i have this error

Short message
Error constructing handler for request of type MediatR.IRequestHandler`2[Grand.Web.Features.Models.ShoppingCart.GetMiniShoppingCart,Grand.Web.Models.ShoppingCart.MiniShoppingCartModel]. Register your handlers with the container. See the samples in GitHub for examples.

i try add httclient to shippingbyweight plugin for add new api
plz help me how to can use httclient  thx