[basex-talk] Error XUST0001 for fold-left ?

Hi,

I just tried a previously (7.8-Snapshot) working application with 8.0-Snapshot and got:

Stopped at /intersect-nodes.xqm, 22/13: [XUST0001] fn:fold-left(items,zero,function): all expressions must be updating or return an empty sequence.

but there are no updates applied in this function (or ones calling this function):

declare %public function _:intersect( $map as map(*)) as node()* { fold-left( map:keys($map), $_:ALL, function($s1, $key as item()*) { let $s2 := $map($key), $a1 := _:all($s1), $a2 := _:all($s2) return if($a1) then if($a2) then $_:ALL else $s2 else if($a2) then $s1 else $s1 intersect $s2 } )

Any ideas?

Regards, Max