[gnome-tweak-tool] extensions: Fix error if GNOME Shell isn't running

[Jeremy Bicha <jbicha src gnome org>]

commit d909b29e972fe7126f2ee4e5d3b798ac75255b94
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Wed Jun 7 14:43:22 2017 -0400

    extensions: Fix error if GNOME Shell isn't running
    
    otherwise Tweak Tool will fail to start

 gtweak/tweaks/tweak_group_shell_extensions.py |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)
---
diff --git a/gtweak/tweaks/tweak_group_shell_extensions.py b/gtweak/tweaks/tweak_group_shell_extensions.py
index 9df3791..e8c39f1 100644
--- a/gtweak/tweaks/tweak_group_shell_extensions.py
+++ b/gtweak/tweaks/tweak_group_shell_extensions.py
@@ -45,14 +45,18 @@ class _ExtensionsBlankState(Gtk.Box):
         self.add(Gtk.Label(label="<b>" + _("No Extensions Installed") + "</b>",
                  use_markup=True, opacity=0.3))
 
-        self._swInfo = Gio.DesktopAppInfo.new("org.gnome.Software.desktop")
-
-        if self._swInfo:
-            btn = Gtk.Button(label=_("Browse in Software"),
-                             always_show_image=True, halign=Gtk.Align.CENTER,
-                             image=Gtk.Image(icon_name="org.gnome.Software-symbolic"))
-            btn.connect("clicked", self._on_browse_clicked)
-            self.add(btn)
+        try:
+            self._swInfo = Gio.DesktopAppInfo.new("org.gnome.Software.desktop")
+
+            if self._swInfo:
+                btn = Gtk.Button(label=_("Browse in Software"),
+                                 always_show_image=True, halign=Gtk.Align.CENTER,
+                                 image=Gtk.Image(icon_name="org.gnome.Software-symbolic"))
+                btn.connect("clicked", self._on_browse_clicked)
+                self.add(btn)
+
+        except:
+            logging.warning("Error detecting shell", exc_info=True)
 
         self.show_all()