wxGUI: set row number properly, fix https://trac.osgeo.org/grass/changeset/32536

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@32540 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/gui_modules/preferences.py

@@ -868,6 +868,7 @@ class PreferencesDialog(wx.Dialog):
         #
         # ask when removing map layer from layer tree
         #
+        row = 0
         askOnRemoveLayer = wx.CheckBox(parent=panel, id=wx.ID_ANY,
                                        label=_("Ask when removing map layer from layer tree"),
                                        name='IsChecked')