Hi Nico, Thanks for the observation. A new stable snapshot with the bug fix is online [1,2]. BaseX 12.3 is scheduled for February or March. Cheers, Christian [1] https://github.com/BaseXdb/basex/issues/2594 [2] https://files.basex.org/releases/latest/ ________________________________ Von: Nico Kutscherauer via BaseX-Talk Gesendet: Mittwoch, 11. Februar 2026 14:08 Bis: basex-talk@mailman.uni-konstanz.de Betreff: [basex-talk] Bug where sorting arrays causes a type error? Hi BaseX team, I have the following simple query: let $strings := ('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j') let $arrays as array(*)* := (array{1 to 2}, array{3 to 6}, array{7 to 9}) let $arrays := sort($arrays, (), fn($seq){array:size($seq) * -1}) let $largest := $arrays => head() return for $idx in $largest?* return $strings[$idx] When I execute it with BaseX 12.2 I get the following suprising error: [XPTY0004] One item expected, 4 found: (3 to 6). Much more suprising is that if I wrap the $arrays?* into a trace call it works: let $strings := ('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j') let $arrays as array(*)* := (array{1 to 2}, array{3 to 6}, array{7 to 9}) let $arrays := sort($arrays, (), fn($seq){array:size($seq) * -1}) let $largest := $arrays => head() return for $idx in trace($largest?*) return $strings[$idx] Result: c d e f The root cause seems to be the sort function. Because if I remove that line it works without the trace. Best Regards, Nico -- Nico Kutscherauer XML Developer data2type GmbH Im Breitspiel 6A 69126 Heidelberg Tel.: +49-(0)6221-73 912 60 www.data2type.de<https://www.data2type.de> Workingdays: Tue/Wed/Thu/Fri(HO) Workinghours: 10-18.30 Company’s head office: Heidelberg Commercial Register court: AG Mannheim HRB 715195 CEO: Manuel Montero Pineda