[gnome-documents/wip/lokdocview-rebase: 14/19] Avoid backtrace when LOK isn't available

[Debarshi Ray <debarshir src gnome org>]

commit ece32af8ec080408f80cd1c5afa78230bde47ea7
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Dec 7 12:10:34 2015 +0100

    Avoid backtrace when LOK isn't available
    
    The error was already showing up, but a backtrace as well.

 src/lokview.js |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/lokview.js b/src/lokview.js
index 49fb4f8..f429fd0 100644
--- a/src/lokview.js
+++ b/src/lokview.js
@@ -144,6 +144,8 @@ const LOKView = new Lang.Class({
     _onLoadStarted: function(manager, doc) {
         if (doc.viewType != Documents.ViewType.LOK)
             return;
+        if (!isAvailable())
+            return;
         let file = Gio.File.new_for_uri (doc.uri);
         let location = file.get_path();
         this._doc = doc;