Saxon

I have a query that is merging two maps:

    map:merge(($module-namespaces, $xquery-namespaces))

Here, the first map has attribute-based keys, while the second has xs:string based keys.

That query succeeds. However, when I call Item.getItemType with a null type hierarchy I get the following exception in Saxon 9.9.1.7:

Caused by: java.lang.NullPointerException
	at net.sf.saxon.type.Type.getCommonSuperType(Type.java:374)
	at net.sf.saxon.ma.map.HashTrieMap.getItemType(HashTrieMap.java:280)
	at net.sf.saxon.ma.map.HashTrieMap.getItemType(HashTrieMap.java:32)
	at net.sf.saxon.type.Type.getItemType(Type.java:213)

Looking at the source code for Type.getCommonSuperType at line 374, it is calling

int r = th.relationship(t1, t2);

without checking that th is null (which is allowed per the documentation on Type.getItemType).

This issue is also present in Saxon 10. The only difference is that the return type has changed to Affinity.