Index: TECH/ListIterator.cls.xml
===================================================================
diff -u -r573 -r1617
--- TECH/ListIterator.cls.xml	(.../ListIterator.cls.xml)	(revision 573)
+++ TECH/ListIterator.cls.xml	(.../ListIterator.cls.xml)	(revision 1617)
@@ -3,7 +3,7 @@
 <Class name="TECH.ListIterator">
 <ClassType/>
 <ProcedureBlock>1</ProcedureBlock>
-<Super>Iterator,%RegisteredObject</Super>
+<Super>TECH.RegisteredObject,TECH.Iterator</Super>
 <Inheritance>right</Inheritance>
 
 <Property name="List">
@@ -42,6 +42,10 @@
 <ProcedureBlock>1</ProcedureBlock>
 <ReturnType>%Status</ReturnType>
 <Implementation><![CDATA[
+	if $$$Not($IsObject(List)) {
+		do ##class(TECH.ExceptionHandler).Throw(##class(TECH.Exceptions.InvalidInputException).%New("Er werd een lijst verwacht"))
+	}
+	
 	Set ..List = List
 	Do ..Reset()
 	Quit $$$OK