ObjectPanel crashes on Windows when applying settings to an object

[j-levy]

Tested on:

• Windows 10 21H1, Lpy 3.0.0 using Python 3.9

Steps to reproduce:

• open the object panel. This can be done directly with the Lpy Studio editor, or simply with python -m openalea.lpy.gui.objectpanel.
• Right clic, New Item, select any new item (I tested with NurbsPatch, NurbsPatch3D and Function, all of them crash).
• Double click on the item to open the settings window
• Click on OK (after doing modifications, or even after not doind any modification)

You would expect : not a crash

You get : a crash with this traceback

Traceback (most recent call last):
  File "c:\users\jonathan\miniconda3\envs\lpy\lib\site-packages\openalea.lpy-3.8.0-py3.8.egg\openalea\lpy\gui\objectpanel.py", line 105, in __transmit_valueChanged__
    self.panel.retrieveObject(self)
  File "c:\users\jonathan\miniconda3\envs\lpy\lib\site-packages\openalea.lpy-3.8.0-py3.8.egg\openalea\lpy\gui\objectpanel.py", line 456, in retrieveObject
    object,objectid = managerDialog.getEditedObject()
TypeError: cannot unpack non-iterable NoneType object

I haven't tested if this happens with Python 3.7 and Python 3.8 too. (openalea.lpy is built for Python 3.7, 3.8 and 3.9 on anaconda.org)