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

        private static void ValidateGettableFieldOrPropertyMember(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.CanRead)
                {
                    throw Error.PropertyDoesNotHaveGetter(pi, nameof(member));
                }
                memberType = pi.PropertyType;
            }
            else
            {
                memberType = fi.FieldType;
            }
        }