Validate in-place causes Zorba Internal Fatal error if a node which might have a simple type contains other nodes

[Federico Cavalieri]

The following query crashes zorba with an Internal fatal error.

Query
import schema namespace d="http://www.zorba-xquery.org/schema" at "upd14.xsd";
import module namespace schema = "http://www.zorba-xquery.com/modules/schema";

declare revalidation lax;

declare variable $doc:=<root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://www.zorba-xquery.org/schema">
<a/>
</root>;

schema:validate-in-place($doc);

Schema

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    targetNamespace="http://www.zorba-xquery.org/schema" xmlns="http://www.zorba-xquery.org/schema"
    elementFormDefault="qualified">

    <xs:element name="root" type="xs:int"/>

</xs:schema>