NullPtrException in saxon:tokenize()

When the argument supplied to saxon:tokenize() is an
empty sequence, the function fails with a
NullPointerException.

This is a side-effect of the change introduced in Saxon
7.6 whereby the XPath "empty sequence" value is mapped
to a Java null.

I have fixed the source code, saxon:tokenize() now
returns an empty sequence if the argument is an empty
sequence.

Of course, XSLT 2.0 stylesheets do not need to call the
saxon:tokenize() extension, it is effectively
superseded by the tokenize() function in the standard
library.

Michael Kay