[planner] Don't crash on an empty print preview, just provide an empty preview.

[Luis Menina <lmenina src gnome org>]

commit 0cc65e2f420af45f78d190ac2af64810a148bb31
Author: Luis Menina <liberforce freeside fr>
Date:   Mon Mar 11 01:00:44 2013 +0100

    Don't crash on an empty print preview, just provide an empty preview.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=581282

 src/planner-print-job.c |   14 +-------------
 1 files changed, 1 insertions(+), 13 deletions(-)
---
diff --git a/src/planner-print-job.c b/src/planner-print-job.c
index 6334037..96267a0 100644
--- a/src/planner-print-job.c
+++ b/src/planner-print-job.c
@@ -237,17 +237,7 @@ print_job_draw_page (GtkPrintOperation *operation,
 
        l = priv->views;
 
-       /* Abort if there is nothing to print.
-        *
-        * A better solution would be to set the number of pages to print to 0
-        * in print_job_begin_print, but 0 is not a valid value for
-        * gtk_print_operation_set_n_pages.
-        */
-       if(!l) {
-               return;
-       }
-
-       while (!page_found) {
+       while (! page_found && l != NULL) {
                v = PLANNER_VIEW (l->data);
 
                pages_in_view = planner_view_print_get_n_pages (v);
@@ -258,8 +248,6 @@ print_job_draw_page (GtkPrintOperation *operation,
                } else {
                        page_nr -= pages_in_view;
                        l = l->next;
-
-                       g_assert (l != NULL);
                }
        }
 }