The issue:Before selecting any item in TreeView, try hold "Shift" key and click on some item

 This will causes an exception in NTreeNodePath class.(FormatException.Input string was not in a correct format).The exception is thrown because the OwnerCollection for selected NLightItem is null and internal array with items doesn't processed correctly.
The exception place: Nevron.UI.WinForm.Controls.dll -> class NTreeNodePath -> method l1lll11I11() -> line this.m_Indices[index] = int.Parse(strArray[index]);

This occurs because strArray  contains one empty item and this item is empty string.