A user create a extended function which calls document function,
ArrayIndexOutOfBoundsException occurs.
When a test case runs, the following exception shows up.
$ ./make.csh    // Compiling test case
$ ./run.csh     // Run test case
node count: 1
node count: 1
ERROR:  '-1'
javax.xml.transform.TransformerException: java.lang.ArrayIndexOutOfBoundsException: -1
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:752)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:357)
        at sample.xslt.Test.main(Test.java:39) 
Caused by: java.lang.ArrayIndexOutOfBoundsException: -1
        at com.sun.org.apache.xml.internal.utils.SuballocatedIntVector.elementAt(SuballocatedIntVector.java:442)
        at com.sun.org.apache.xml.internal.dtm.ref.sax2dtm.SAX2DTM2._exptype(SAX2DTM2.java:1905)
        at com.sun.org.apache.xml.internal.dtm.ref.DTMDefaultBase.getNodeType(DTMDefaultBase.java:1838)
        at com.sun.org.apache.xalan.internal.xsltc.dom.SAXImpl.getNodeName(SAXImpl.java:1055)
        at com.sun.org.apache.xml.internal.dtm.ref.DTMNodeProxy.getNodeName(DTMNodeProxy.java:188)
        at sample.xslt.ExtFunc.test(ExtFunc.java:12)
        at GregorSamsa.template$dot$0()
        at GregorSamsa.applyTemplates()
        at GregorSamsa.transform()
        at com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet.transform(AbstractTranslet.java:617)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:745)
        ... 2 more
---------
java.lang.ArrayIndexOutOfBoundsException: -1
        at com.sun.org.apache.xml.internal.utils.SuballocatedIntVector.elementAt(SuballocatedIntVector.java:442)
        at com.sun.org.apache.xml.internal.dtm.ref.sax2dtm.SAX2DTM2._exptype(SAX2DTM2.java:1905)
        at com.sun.org.apache.xml.internal.dtm.ref.DTMDefaultBase.getNodeType(DTMDefaultBase.java:1838)
        at com.sun.org.apache.xalan.internal.xsltc.dom.SAXImpl.getNodeName(SAXImpl.java:1055)
        at com.sun.org.apache.xml.internal.dtm.ref.DTMNodeProxy.getNodeName(DTMNodeProxy.java:188)
        at sample.xslt.ExtFunc.test(ExtFunc.java:12)
        at GregorSamsa.template$dot$0()
        at GregorSamsa.applyTemplates()
        at GregorSamsa.transform()
        at com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet.transform(AbstractTranslet.java:617)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:745)
        at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:357)
        at sample.xslt.Test.main(Test.java:39)