[BUG] Jaxp does not let you validate XML Schema validity

[ahenket]

We have a routine that validates instances against self-generated xsds. It's a rare thing but every once in a while, the xsd itself is in question, so instead of marking every instance as invalid I would like to notify that the schema itself is invalid.

The way to do that seems to be:
validation:jaxp(xs:anyURI('my.xsd'), true())
validation:jaxp(xs:anyURI('my.xsd'), false())

(both always return false() regardless of schema validity)
or

validation:pre-parse-grammar(xs:anyURI('my.xsd'))
(returns “Cannot invoke “Object.toString()” because “value” is null”)

validation:pre-parse-grammar(doc('my.xsd'))
(returns “Only XMLSchemas can be preparsed.“)

Environment
eXist-db 6.2 - Any hints? Obviously “my.xsd” is something that resolves when I run it

[dizzzz]

Please could you check if cleaning the grammar cache solves the issue?

if the pre-parse fails (quite ugly i'd say) I guess a crucial errorhandling is missing;

is there anything in the logs? Can you share the XSD?