Comment 0 for bug 1762779

To reproduce:

1. Open panel switcher.
2. Click "Save Configuration" button.
3. Click "Save Configuration" button.

Result:

Nothing happens. The window does not close, and clicking cancel no longer works either. The following error is printed on the terminal:

:~$ xfpanel-switch
Traceback (most recent call last):
  File "/usr/share/xfpanel-switch/xfpanel-switch/xfpanel-switch.py", line 221, in on_save_clicked
    self.save_configuration(name)
  File "/usr/share/xfpanel-switch/xfpanel-switch/xfpanel-switch.py", line 209, in save_configuration
    PanelConfig.from_xfconf(self.xfconf).to_file(filename)
  File "/usr/share/xfpanel-switch/xfpanel-switch/panelconfig.py", line 63, in from_xfconf
    pc.find_desktops()
  File "/usr/share/xfpanel-switch/xfpanel-switch/panelconfig.py", line 113, in find_desktops
    if self.check_desktop(desktop_path):
  File "/usr/share/xfpanel-switch/xfpanel-switch/panelconfig.py", line 87, in check_desktop
    bytes = self.get_desktop_source_file(path).read()
  File "/usr/share/xfpanel-switch/xfpanel-switch/panelconfig.py", line 125, in get_desktop_source_file
    if self.source is None:
AttributeError: 'PanelConfig' object has no attribute 'source'

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xfpanel-switch 1.0.6-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
CurrentDesktop: XFCE
Date: Tue Apr 10 17:23:14 2018
InstallationDate: Installed on 2018-04-10 (0 days ago)
InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180410)
PackageArchitecture: all
SourcePackage: xfpanel-switch
UpgradeStatus: No upgrade log present (probably fresh install)