Index: sources/gui/qml/pages/posttreatment/PostTreatmentBase.qml
===================================================================
diff -u -r18e4634800357ac1d8bc1da1cad04836ba85d33c -r7fb13d9e1a453a37ab4dea5536e0f19ed6e272d2
--- sources/gui/qml/pages/posttreatment/PostTreatmentBase.qml	(.../PostTreatmentBase.qml)	(revision 18e4634800357ac1d8bc1da1cad04836ba85d33c)
+++ sources/gui/qml/pages/posttreatment/PostTreatmentBase.qml	(.../PostTreatmentBase.qml)	(revision 7fb13d9e1a453a37ab4dea5536e0f19ed6e272d2)
@@ -33,11 +33,9 @@
     onVisibleChanged: if (visible) { _root.updateModel() }
 
     function updateModel () {
-        let  stepName = stepNames[stackStepIndex]
-        if ( stepName === undefined ) stepName = ""
+        let stepName = stepNames[stackStepIndex] ?? ""
+        let group    = vSettings.groupFormat(stepName, _root.subStepName.length === 0 ? "" : _root.subStepName )
 
-        let group = vSettings.groupFormat(stepName, _root.subStepName.length === 0 ? "" : _root.subStepName )
-
         let instructionsGroup    = vSettings.instructions[group]
 
         if ( instructionsGroup !== undefined ) {