[rygel] server: Report missing filter in Browse

[Jens Georg <jensgeorg src gnome org>]

commit 471708c90dc7fe3ea1cfb1ff2629d18527bedf98
Author: Jens Georg <jensg openismus com>
Date:   Tue Aug 6 11:51:38 2013 +0200

    server: Report missing filter in Browse

 src/librygel-server/rygel-media-query-action.vala |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/librygel-server/rygel-media-query-action.vala 
b/src/librygel-server/rygel-media-query-action.vala
index 774f24c..b0b5b0a 100644
--- a/src/librygel-server/rygel-media-query-action.vala
+++ b/src/librygel-server/rygel-media-query-action.vala
@@ -120,6 +120,10 @@ internal abstract class Rygel.MediaQueryAction : GLib.Object, StateMachine {
                                         (_("Invalid range"));
         }
 
+        if (this.filter == null) {
+            throw new ContentDirectoryError.INVALID_ARGS (_("Missing filter"));
+        }
+
         this.index = (uint) index;
         this.requested_count = (uint) requested_count;