Adding a radio button causes a error

When adding a radio button to a sizer, an error occurs. 

Steps to reproduce:

Create a new frame.
Drag a radio button onto the design window.

This error occurs:

ERROR   : None
An unexpected error occurred!

Exception type:      <class 'NameError'>
Exception details:   name 'label' is not defined

Application stack traceback:
  File "/Users/user/Documents/Development/Projects/Python/wxGlade/edit_base.py", line 700, in on_drop_widget
    new_widget = common.widgets[common.widget_to_add](self.parent, self.pos)
  File "/Users/user/Documents/Development/Projects/Python/wxGlade/widgets/radio_button/radio_button.py", line 63, in builder
    editor = EditRadioButton(label, parent, label, pos)

Date and time:       2019-08-24T09:53:35.250757
Python version:      3.7.2
wxPython version:    4.0.3
wxWidgets platform:  __WXMAC__
wxGlade version:     0.9.9pre