[libchamplain] Fix return value error in champlain_view_get_world

[Jiří Techet <jiritechet src gnome org>]

commit 09a1b432165ecdc587ea8168a4b0c29a826f9c85
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Wed Sep 2 01:32:38 2015 +0800

    Fix return value error in champlain_view_get_world
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754413

 champlain/champlain-view.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/champlain/champlain-view.c b/champlain/champlain-view.c
index 48df08c..2aa7436 100644
--- a/champlain/champlain-view.c
+++ b/champlain/champlain-view.c
@@ -1840,7 +1840,7 @@ champlain_view_set_max_zoom_level (ChamplainView *view,
 ChamplainBoundingBox *
 champlain_view_get_world (ChamplainView *view)
 {
-  g_return_if_fail (CHAMPLAIN_IS_VIEW (view));
+  g_return_val_if_fail (CHAMPLAIN_IS_VIEW (view), NULL);
 
   ChamplainViewPrivate *priv = view->priv;