[f-spot] Avoid NRE.

[Ruben Vermeersch <rubenv src gnome org>]

commit 4fdb5affde5cfcdad532b781f9d65a424d05470b
Author: Ruben Vermeersch <ruben savanne be>
Date:   Sat Aug 7 23:45:23 2010 +0200

    Avoid NRE.

 src/Widgets/IconView.cs |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/Widgets/IconView.cs b/src/Widgets/IconView.cs
index 92a8f90..5f3ba09 100644
--- a/src/Widgets/IconView.cs
+++ b/src/Widgets/IconView.cs
@@ -1115,6 +1115,9 @@ namespace FSpot.Widgets
 			int i, cell_num;
 			//Preload (area, false);
 
+			if (collection == null)
+				return;
+
 			for (i = 0, cell_num = start_cell_num;
 			     i < num_rows && cell_num < collection.Count;
 			     i ++) {