[gnome-shell] extension: log message if extension could not be installed

[Marco Trevisan <marcotrevi src gnome org>]

commit 35a9c3ec867afa6359ebc27a00588ceddbda7e2a
Author: Gautier Pelloux-Prayer <gautier+git damsy net>
Date:   Fri Jan 6 13:08:29 2017 +0100

    extension: log message if extension could not be installed
    
    https://bugzilla.gnome.org/show_bug.cgi?id=776940

 js/ui/extensionDownloader.js |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/extensionDownloader.js b/js/ui/extensionDownloader.js
index 03441e6..fd2ecfe 100644
--- a/js/ui/extensionDownloader.js
+++ b/js/ui/extensionDownloader.js
@@ -233,7 +233,9 @@ var InstallExtensionDialog = new Lang.Class({
         let dir = Gio.File.new_for_path(GLib.build_filenamev([global.userdatadir, 'extensions', uuid]));
         let invocation = this._invocation;
         function errback(code, message) {
-            invocation.return_dbus_error('org.gnome.Shell.' + code, message ? message.toString() : '');
+            let msg = message ? message.toString() : '';
+            log('Error while installing %s: %s (%s)'.format(uuid, code, msg));
+            invocation.return_dbus_error('org.gnome.Shell.' + code, msg);
         }
 
         function callback() {