nullpointer when using foreach on a root object's collection

In the attached test case test0, test2 and test3 work as expected, but test1 throws a nullpointer exception. This occurs when a template iterates over a collection of the root object, or a collection of a property of a root object. The tests show that the error does not occur when the collection is a property of an entry in the map

Eg

test0 - works
String template = "@foreach

a@end{}";
Map map = new HashMap();
map.put("list",list);
String r = TemplateInterpreter.evalToString(template,map);

test1 - fails
Folder f1 = new Folder("f1",null);
String template = "@

@foreach

a@end{}";
String r = TemplateInterpreter.evalToString(template,f1);

class Folder extends Page