Index: sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml
===================================================================
diff -u -r07121b02499a4c929c5b5e8bd804a67539574c1b -r4fd94e57fbbdb54c779f28ef50f0997e8eefee5f
--- sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml	(.../PreTreatmentBase.qml)	(revision 07121b02499a4c929c5b5e8bd804a67539574c1b)
+++ sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml	(.../PreTreatmentBase.qml)	(revision 4fd94e57fbbdb54c779f28ef50f0997e8eefee5f)
@@ -34,11 +34,9 @@
 
     // update model for instruction based steps
     function updateModel () {
-        let  stepName = stepNames[stackStepIndex]
-        if ( stepName === undefined ) stepName = ""
+        let stepName = stepNames[stackStepIndex] ?? ""
+        let group    = vSettings.groupFormat(stepName, vSettings.advancedMode || _root.subStepName.length === 0 ? "" : _root.subStepName )
 
-        let group = vSettings.groupFormat(stepName, vSettings.advancedMode || _root.subStepName.length === 0 ? "" : _root.subStepName )
-
         let instructionsGroup    = vSettings.instructions[group]
 
         if ( instructionsGroup !== undefined ) {