[gthumb] fixed error when the debug code is active

[Paolo Bacchilega <paobac src gnome org>]

commit b8fb135019f68e18313fe29264310dbba7a03305
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Mon Dec 8 23:49:27 2014 +0100

    fixed error when the debug code is active

 gthumb/gth-image-preloader.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gthumb/gth-image-preloader.c b/gthumb/gth-image-preloader.c
index 24016a7..2159380 100644
--- a/gthumb/gth-image-preloader.c
+++ b/gthumb/gth-image-preloader.c
@@ -777,7 +777,10 @@ gth_image_preloader_load (GthImagePreloader         *self,
        va_list      args;
 
 #ifdef DEBUG_PRELOADER
-       g_print ("request %s @%d\n", g_file_get_uri (requested->file), requested_size);
+       if (requested != NULL)
+               g_print ("request %s @%d\n", g_file_get_uri (requested->file), requested_size);
+       else
+               g_print ("request modified image @%d\n", requested_size);
 #endif
 
        request = load_request_new (self);