[gnome-maps] build: Fix "non-void function should return a value"

[Jonas Danielsson <jonasdn src gnome org>]

commit daa7ee4eb1ed7edaf9b6bede1164698408f5ab96
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Sun Sep 13 00:44:38 2015 +0800

    build: Fix "non-void function should return a value"
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754926

 lib/maps-file-tile-source.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/lib/maps-file-tile-source.c b/lib/maps-file-tile-source.c
index a3a07ec..8d11e7d 100644
--- a/lib/maps-file-tile-source.c
+++ b/lib/maps-file-tile-source.c
@@ -471,8 +471,8 @@ gboolean
 maps_file_tile_source_prepare (MapsFileTileSource *tile_source,
                                GError            **error)
 {
-  g_return_if_fail (MAPS_IS_FILE_TILE_SOURCE (tile_source));
-  g_return_if_fail (tile_source->priv->path != NULL);
+  g_return_val_if_fail (MAPS_IS_FILE_TILE_SOURCE (tile_source), FALSE);
+  g_return_val_if_fail (tile_source->priv->path != NULL, FALSE);
 
   ChamplainMapSource *source = (ChamplainMapSource *) tile_source;
   gboolean ret = TRUE;