wxNviz: fix error from https://trac.osgeo.org/grass/ticket/1961, comment 15

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@56578 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/nviz/mapwindow.py

@@ -1264,8 +1264,8 @@ class GLWindow(MapWindow, glcanvas.GLCanvas):
             if 'object' not in data['surface']:
                 return 0
         elif layer.type ==  'vector':
-            if 'object' not in data['vlines'] and \
-                    'object' not in data['points']:
+            if 'object' not in data['vector']['lines'] and \
+                    'object' not in data['vector']['points']:
                 return 0
         
         return 1