Another bug in Chicago95 plus

Debian 12 bookworm
```
Traceback (most recent call last):
File "/home/sparky4/p/Chicago95/./Plus/PlusGUI.py", line 1312, in install_accept
self.install_theme()
File "/home/sparky4/p/Chicago95/./Plus/PlusGUI.py", line 1337, in install_theme
self.theme.go(cursors=self.install_cursors, icons=self.install_icons, wallpaper=self.install_wallpaper,
File "/home/sparky4/p/Chicago95/Plus/pluslib.py", line 160, in go
self.enable_theme(cursors, icons, wallpaper, sounds, colors, fonts, screensaver)
File "/home/sparky4/p/Chicago95/Plus/pluslib.py", line 3098, in enable_theme
if self.theme_config['wallpaper']['theme_wallpaper'] and self.theme_config['wallpaper']['theme_wallpaper']['new_filename']:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
KeyError: 'new_filename'
```

sorry to bother you here is the error