System.Linq.Expressions.Expression.ValidateSettableFieldOrPropertyMember C# (CSharp) Method

        private static void ValidateSettableFieldOrPropertyMember(MemberInfo member, out Type memberType)
        {
            FieldInfo fi = member as FieldInfo;
            if (fi == null)
            {
                PropertyInfo pi = member as PropertyInfo;
                if (pi == null)
                {
                    throw Error.ArgumentMustBeFieldInfoOrPropertyInfo(nameof(member));
                }
                if (!pi.CanWrite)
                {
                    throw Error.PropertyDoesNotHaveSetter(pi, nameof(member));
                }
                memberType = pi.PropertyType;
            }
            else
            {
                memberType = fi.FieldType;
            }
        }
    }