Index: /home/sebp/workspace/deskbar-applet-2.20/deskbar/core/CoreImpl.py
===================================================================
--- /home/sebp/workspace/deskbar-applet-2.20/deskbar/core/CoreImpl.py	(revision 1735)
+++ /home/sebp/workspace/deskbar-applet-2.20/deskbar/core/CoreImpl.py	(working copy)
@@ -336,5 +336,8 @@
             
     def forward_query_ready(self, handler, query, matches):
         if query == self._last_query and matches != None and len(matches) > 0 and not self._stop_queries:
+            for m in matches:
+                if m == None:
+                    raise Exception, "Handler %s with query %s returned None as a match" % (handler, query)   
             self._emit_query_ready(matches)
         
\ No newline at end of file
