when create new signup content, i got notice error

Notice: Trying to get property of non-object in signup_alter_node_form() (line 161 of /var/www/pressflow6/sites/all/modules/signup/includes/node_form.inc).

to solve this, i need to change 161 lines to

'#default_value' => ($node) ? $node->signup_user_reg_form : '',

because $node is null.