Index: /home/sebp/workspace/deskbar-applet/deskbar/core/Indexer.py
===================================================================
--- /home/sebp/workspace/deskbar-applet/deskbar/core/Indexer.py	(revision 1706)
+++ /home/sebp/workspace/deskbar-applet/deskbar/core/Indexer.py	(working copy)
@@ -20,6 +20,8 @@
         self.d = {}
 
     def add(self, key, obj):
+        if obj == None:
+            raise ValueError, "Tried to add None for key '%s'" % key
         key = key.lower()
         for tok in key.split():
             # Filter out some words not worth indexing
Index: /home/sebp/workspace/deskbar-applet/deskbar/handlers/programs.py
===================================================================
--- /home/sebp/workspace/deskbar-applet/deskbar/handlers/programs.py	(revision 1706)
+++ /home/sebp/workspace/deskbar-applet/deskbar/handlers/programs.py	(working copy)
@@ -246,6 +246,8 @@
         result = []
         for match in self._indexer.look_up(query):
             match._priority = get_priority_for_name(query, match._desktop.get_string("Exec"))
+            if match == None:
+                raise ValueError, "Error when retrieving match for query '%s'" % query
             result.append(match)
         return result
             
