[gnome-control-center] wacom: Don't crash if created devices don't exist

[Bastien Nocera <hadess src gnome org>]

commit d5623b731ef6b2b486e0ccecbf852ef434e7841e
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Dec 12 18:17:24 2011 +0000

    wacom: Don't crash if created devices don't exist

 panels/wacom/test-wacom.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/panels/wacom/test-wacom.c b/panels/wacom/test-wacom.c
index a0287ba..2743ad6 100644
--- a/panels/wacom/test-wacom.c
+++ b/panels/wacom/test-wacom.c
@@ -9,6 +9,9 @@ add_page (GList *devices,
 	GsdWacomDevice *stylus, *eraser;
 	GList *l;
 
+	if (devices == NULL)
+		return;
+
 	stylus = eraser = NULL;
 	for (l = devices; l ; l = l->next) {
 		switch (gsd_wacom_device_get_device_type (l->data)) {