[totem] main: Avoid warning when state.ini doesn't exist

[Bastien Nocera <hadess src gnome org>]

commit 787887e14923a8391a1206f3e1b4e852533a3d3c
Author: Bastien Nocera <hadess hadess net>
Date:   Fri Jul 1 10:35:10 2011 +0100

    main: Avoid warning when state.ini doesn't exist
    
    As there will not be a page_id to reset to.

 src/totem-sidebar.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/totem-sidebar.c b/src/totem-sidebar.c
index d6edbc7..ff48d58 100644
--- a/src/totem-sidebar.c
+++ b/src/totem-sidebar.c
@@ -297,6 +297,9 @@ totem_sidebar_set_current_page (Totem *totem,
 {
 	int page_num;
 
+	if (page_id == NULL)
+		return;
+
 	page_num = get_page_num_for_name (totem, page_id);
 
 	if (page_num == -1) {