Pressing "About Lollypop" crashes program if in adaptive mode
Program crashes if pressing the "About lollypop" menu item when the window is in the "small" mode.
Traceback (most recent call last):
File "/usr/lib/python3.7/site-packages/lollypop/application_actions.py", line 271, in __on_about_activate
about_headerbar.set_show_close_button(False)
AttributeError: 'NoneType' object has no attribute 'set_show_close_button'