[banshee] [PlayQueue] Fixed a NRE when deleting the selected playlist (bgo#595018)

[Alexander Kojevnikov <alexk src gnome org>]

commit fa14e0a29e6a2ca334a90627023665deb93ca320
Author: Alexander Kojevnikov <alexander kojevnikov com>
Date:   Mon Sep 14 14:22:07 2009 +1000

    [PlayQueue] Fixed a NRE when deleting the selected playlist (bgo#595018)

 .../Banshee.PlayQueue/PlayQueueSource.cs           |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/src/Extensions/Banshee.PlayQueue/Banshee.PlayQueue/PlayQueueSource.cs b/src/Extensions/Banshee.PlayQueue/Banshee.PlayQueue/PlayQueueSource.cs
index 217a9b0..82d5b0f 100644
--- a/src/Extensions/Banshee.PlayQueue/Banshee.PlayQueue/PlayQueueSource.cs
+++ b/src/Extensions/Banshee.PlayQueue/Banshee.PlayQueue/PlayQueueSource.cs
@@ -132,6 +132,11 @@ namespace Banshee.PlayQueue
             };
             header_widget.SourceChanged += delegate(object sender, SourceChangedEventArgs e) {
                 populate_from = e.Value;
+                if (populate_from == null) {
+                    populate_from_name = "";
+                    PopulateFromSchema.Set ("");
+                    return;
+                }
                 populate_from_name = e.Value.Name;
                 PopulateFromSchema.Set (e.Value.Name);
                 source_set_at = DateTime.Now;