kivy wizard: fix bug if password is not provided

gui/kivy/uix/dialogs/installwizard.py

@@ -808,7 +808,7 @@ class InstallWizard(BaseWizard, Widget):
             if pin:
                 self.run('confirm_password', pin, run_next)
             else:
-                run_next(None)
+                run_next(None, None)
         self.password_dialog('Choose a PIN code', callback)
 
     def confirm_password(self, pin, run_next):

gui/kivy/uix/dialogs/password_dialog.py

@@ -70,6 +70,7 @@ Builder.load_string('''
                 text: _('Cancel')
                 on_release:
                     popup.dismiss()
+                    popup.callback(None)
 ''')