Bunch of Errors when loading course xml-file

[TinyCrocodile]

Error Text: "System.NullReferenceException" no more information provided
Exeption is thown when loading Course XML-File
Unknown Source

• Investigate error source
  The Errors where coming from the attempt to get the name of a not existing folder in the generation of the tooltips.
• Improve errorhandling
  The error is now avoided by checking the folder for nothing bevore trying to get the name. If the folder is nothing then "Root" ist displayed in the tooltips