[gitg/vala] Allow populating with a NULL navigation

[Jesse van den Kieboom <jessevdk src gnome org>]

commit 1b9a01fc7d1feb39bd85db6f0b2a10abe45182a9
Author: Jesse van den Kieboom <jesse vandenkieboom epfl ch>
Date:   Tue Jul 17 09:46:05 2012 +0200

    Allow populating with a NULL navigation

 libgitg-ext/gitg-ext-navigation-tree-view.vala |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/libgitg-ext/gitg-ext-navigation-tree-view.vala b/libgitg-ext/gitg-ext-navigation-tree-view.vala
index e44cc9b..806fb00 100644
--- a/libgitg-ext/gitg-ext-navigation-tree-view.vala
+++ b/libgitg-ext/gitg-ext-navigation-tree-view.vala
@@ -57,6 +57,7 @@ public class NavigationTreeModel : Gtk.TreeStore
 			}
 		}
 	}
+
 	private SList<Gtk.TreeIter?> d_parents;
 	private uint d_sections;
 	private uint d_oid;
@@ -148,8 +149,13 @@ public class NavigationTreeModel : Gtk.TreeStore
 		return this;
 	}
 
-	public uint populate(GitgExt.Navigation nav)
+	public uint populate(GitgExt.Navigation? nav)
 	{
+		if (nav == null)
+		{
+			return 0;
+		}
+
 		uint ret = begin_section();
 
 		nav.populate(this);