system.tag.browseHistorialTags and UDT in without folders

I’m implementing a dynamic chart, so I’m using system.tag.browseHistoricalTags to iterate throught it. Found out that if I have a UDT inside the tag provider without any folder holding it

 def browse(path='histprov:DB:/drv:server:tagprovider:/tag:'):
    for result in system.tag.browseHistoricalTags(path).getResults():
        print result
        if result.hasChildren():

will return

Result[displayPath=null, path=histprov:DB:/drv:server:provider:/tag:/anyfolder, hasChildren=true, type=null]
Traceback (most recent call last):
  File "<input>", line 6, in <module>
  File "<input>", line 5, in browse
  File "<input>", line 2, in browse
TypeError: 'NoneType' object is not iterable

If I put the UDT Instances inside a folder the code runs without any problem.