SaxonJS 3.0.0-beta2: xslt3-he crashes with 'Internal error: assertion failed'

[ThePlenkov]

Description

When I run an XSLT 3.0 stylesheet that builds a JSON map/array structure using SaxonJS 3.0.0-beta2 (via the xslt3-he CLI), the compiler aborts with Internal error: assertion failed. The same logic works with SaxonJS 2.x.

Steps to Reproduce

1. Save the following stylesheet as adt-to-json.xsl:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="3.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:pak="http://www.sap.com/adt/packages"
  xmlns:adtcore="http://www.sap.com/adt/core"
  xmlns:atom="http://www.w3.org/2005/Atom"
  xmlns:pkg="urn:pkg"
  exclude-result-prefixes="xs pak adtcore atom pkg">

  <xsl:output method="json" indent="yes" encoding="UTF-8"/>

  <xsl:function name="pkg:boolean" as="xs:boolean">
    <xsl:param name="value" as="xs:string?"/>
    <xsl:sequence select="lower-case($value) = ('true', '1', 'x')"/>
  </xsl:function>

  <xsl:template match="/">
    <xsl:sequence select="pkg:package-map(/pak:package)"/>
  </xsl:template>

  <xsl:function name="pkg:package-map" as="map(*)">
    <xsl:param name="pkg" as="element(pak:package)"/>

    <xsl:sequence select="
      map {
        'core': map {
          'name': string($pkg/@adtcore:name),
          'description': string($pkg/@adtcore:description)
        },
        'package': map {
          'attributes': map {
            'packageType': string($pkg/pak:attributes/@pak:packageType),
            'isPackageTypeEditable': pkg:boolean($pkg/pak:attributes/@pak:isPackageTypeEditable)
          },
          'links': array {
            for $link in $pkg/atom:link
            return map {
              'rel': string($link/@rel),
              'href': string($link/@href),
              'title': string($link/@title),
              'type': string($link/@type)
            }
          },
          'useAccesses': map {
            'isVisible': pkg:boolean($pkg/pak:useAccesses/@pak:isVisible)
          }
        }
      }
    "/>
  </xsl:function>

</xsl:stylesheet>

2. Save this minimal source XML as package.xml:

<pak:package xmlns:pak="http://www.sap.com/adt/packages" xmlns:adtcore="http://www.sap.com/adt/core" xmlns:atom="http://www.w3.org/2005/Atom"
  adtcore:responsible="PPLENKOV" adtcore:masterLanguage="EN" adtcore:name="$ABAPGIT_EXAMPLES" adtcore:type="DEVC/K"
  adtcore:changedAt="2025-11-09T00:00:00Z" adtcore:version="active" adtcore:createdAt="2025-11-09T00:00:00Z"
  adtcore:changedBy="PPLENKOV" adtcore:createdBy="PPLENKOV" adtcore:description="Abapgit examples"
  adtcore:descriptionTextLimit="60" adtcore:language="EN">
  <atom:link href="versions" rel="http://www.sap.com/adt/relations/versions" title="Historic versions"/>
  <pak:attributes pak:packageType="development" pak:isPackageTypeEditable="false"
    pak:isAddingObjectsAllowed="false" pak:isAddingObjectsAllowedEditable="true" pak:isEncapsulated="false"
    pak:isEncapsulationEditable="false" pak:isEncapsulationVisible="false" pak:recordChanges="false"
    pak:isRecordChangesEditable="false" pak:isSwitchVisible="false" pak:languageVersion=""
    pak:isLanguageVersionVisible="true" pak:isLanguageVersionEditable="true"/>
  <pak:useAccesses pak:isVisible="false"/>
</pak:package>

3. Run the CLI shipped with SaxonJS 3:

npx xslt3-he@3.0.0-beta2 -xsl:adt-to-json.xsl -s:package.xml -o:out.json

Actual result

The CLI exits with:

Internal error: assertion failed
    at SaxonJS3N.js:3755:396
    ... (full stack omitted for brevity)

No output is produced.

Expected result

The stylesheet should serialize the JSON map/array just as SaxonJS 2.x and SaxonJ 10/11 do.

Environment

• xslt3-he / saxonjs-he: 3.0.0-beta2 (npm install)
• Node.js 24.10.0 on Ubuntu 22.04 (WSL)

Let me know if you need the full stack trace or the original, larger stylesheet—the reproducer above consistently fails for me.

Generated by Codex

[michaelhkay]

Transferred to https://saxonica.plan.io/issues/6943 - please track progress there.