Traceback (most recent call last):
  File "/usr/share/pythoncad/PythonCAD/Interface/Gtk/gtkimage.py", line 356, in __destroyEvent
    self.close()
  File "/usr/share/pythoncad/PythonCAD/Interface/Gtk/gtkimage.py", line 332, in close
    _image.close()
  File "/usr/share/pythoncad/PythonCAD/Generic/image.py", line 358, in close
    _layer.clear()
  File "/usr/share/pythoncad/PythonCAD/Generic/layer.py", line 294, in clear
    self.delObject(_obj)
  File "/usr/share/pythoncad/PythonCAD/Generic/layer.py", line 952, in delObject
    self.__delHCLine(obj)
  File "/usr/share/pythoncad/PythonCAD/Generic/layer.py", line 1174, in __delHCLine
    hcl.finish()
  File "/usr/share/pythoncad/PythonCAD/Generic/hcline.py", line 82, in finish
    self.__keypoint.disconnect(self)
  File "/usr/share/pythoncad/PythonCAD/Generic/message.py", line 76, in disconnect
    _methods.remove(_method)
  File "/usr/share/pythoncad/PythonCAD/Generic/hcline.py", line 62, in __eq__
    if abs(self.getLocation().y - obj.getLocation().y) < 1e-10:
AttributeError: 'NoneType' object has no attribute 'y'