[Help-smalltalk] What to do with this backtrace: VFS.VFSHandler nameIn: ''!

[Bram Neijt]

Hi, I've got the following backtrace I don't know how to handle:

VFS.VFSHandler nameIn: ''!

Gives the backtrace:
Object: #VFS error: did not understand #between:and:
Symbol(Object)>>#primError:
MessageNotUnderstood(Exception)>>#defaultAction
optimized [] in Exception class>>#coreException
MessageNotUnderstood(Signal)>>#activateHandler:
MessageNotUnderstood(Exception)>>#signal
Symbol(Object)>>#doesNotUnderstand:
String(SequenceableCollection)>>#at:ifAbsent:
Namespace>>#nameIn:
VFS.VFSHandler class(ClassDescription)>>#nameIn:
UndefinedObject>>#executeStatements
nil


How can I find the class name and overcome this problem? It works for
other classes just fine (for example: String nameIn: ''!)

Greetings,
 Bram