TypeError for unknown encoding (like windows-1250)

[Eccenux]

1. Go to http://syssgx.github.io/xml.js/.
2. Paste xml and xsd with unknow encoding (examples below).
3. Push the Validate button. -> fails with TypeError.

Micro XML file:

<?xml version="1.0" encoding="windows-1250"?>
<czytelnicy xsi:noNamespaceSchemaLocation="ImpCz.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
</czytelnicy>

Micro XSD file:

<?xml version="1.0" encoding="windows-1250"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
	<xs:element name="czytelnicy"></xs:element>
</xs:schema>

Current behaviour:

Uncaught TypeError: Gt is not a function
    at xn (xmllint.js:2)
    at Up (xmllint.js:2)
    at ns (xmllint.js:2)
    at pi (xmllint.js:2)
    at cj (xmllint.js:2)
    at Wi (xmllint.js:2)
    at eE (xmllint.js:2)
    at ig (xmllint.js:2)
    at nd (xmllint.js:2)
    at Object.Hga (xmllint.js:2)