not working

I am getting the following error when executing the code:

from direct.showbase.ShowBase import ShowBase

base = ShowBase()

panda = loader.loadModel("models/panda")
Assertion failed: !is_empty() at line 315 of panda/src/pgraph/nodePath.cxx Traceback (most recent call last): File "", line 1, in File "C:\Panda3D-1.10.8-x64\direct\extensions_native\", line 409, in place base.startDirect(fWantTk = 1) File "C:\Panda3D-1.10.8-x64\direct\showbase\", line 3284, in startD irect = DirectSession.DirectSession() File "C:\Panda3D-1.10.8-x64\direct\directtools\", line 54, in __init__ self.manipulationControl = DirectManipulationControl() File "C:\Panda3D-1.10.8-x64\direct\directtools\", line 12 , in __init__ self.objectHandles = ObjectHandles() File "C:\Panda3D-1.10.8-x64\direct\directtools\", line 10 77, in __init__ self.xPostGroup = self.xHandles.find('**/x-post-group') AssertionError: !is_empty() at line 315 of panda/src/pgraph/nodePath.cxx

What should I change in the file?

It’s in direct/directtools/
Change this line:

self.scalingNode = self.getChild(0)

To this:

self.scalingNode = NodePath(self)

Thanks! It worked. Now can you explain how the works?