Fixed generic method instantiation and extended last fix to nonvirtual properties too

IPA.Loader/Config/Stores/GeneratedStoreImpl.cs

@@ -1604,9 +1604,10 @@ namespace IPA.Config.Stores
 
                 // for now, we assume that its a generated type implementing IGeneratedStore
                 var IGeneratedStore_Serialize = typeof(IGeneratedStore).GetMethod(nameof(IGeneratedStore.Serialize));
-                var IGeneratedStoreT_CopyFrom = typeof(IGeneratedStore<>).GetMethod(nameof(IGeneratedStore<object>.CopyFrom));
+                var IGeneratedStoreT_CopyFrom = typeof(IGeneratedStore<>).GetMethod(nameof(IGeneratedStore<object>.CopyFrom))
+                    .MakeGenericMethod(member.Type);
 
-                if (member.IsField)
+                if (!member.IsVirtual)
                 {
                     var noCreate = il.DefineLabel();
                     var stlocal = GetLocal(member.Type);