[bijiben] get_last_change_date_str : add exceptions

[Pierre-Yves Luyten <pyluyten src gnome org>]

commit b84e95e76d5e4d36ac6c1743d821684045f6168c
Author: Pierre-Yves Luyten <py luyten fr>
Date:   Wed Jul 8 00:46:15 2015 +0200

    get_last_change_date_str : add exceptions
    
    This function sometimes crashes.
    See rh BZ#1204815

 src/libbiji/biji-note-id.c  |    4 ++++
 src/libbiji/biji-note-obj.c |    2 ++
 2 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/src/libbiji/biji-note-id.c b/src/libbiji/biji-note-id.c
index e4d515a..a64a795 100644
--- a/src/libbiji/biji-note-id.c
+++ b/src/libbiji/biji-note-id.c
@@ -261,6 +261,8 @@ biji_note_id_get_content (BijiNoteID *id)
 gint64
 biji_note_id_get_mtime (BijiNoteID *n)
 {
+  g_return_val_if_fail (BIJI_IS_NOTE_ID (n), 0);
+
   return n->priv->mtime;
 }
 
@@ -268,6 +270,8 @@ biji_note_id_get_mtime (BijiNoteID *n)
 gboolean
 biji_note_id_set_mtime (BijiNoteID *n, gint64 time)
 {
+  g_return_if_fail (BIJI_IS_NOTE_ID (n));
+
   if (n->priv->mtime != time)
   {
     n->priv->mtime = time;
diff --git a/src/libbiji/biji-note-obj.c b/src/libbiji/biji-note-obj.c
index 34eba31..c69295c 100644
--- a/src/libbiji/biji-note-obj.c
+++ b/src/libbiji/biji-note-obj.c
@@ -370,6 +370,8 @@ biji_note_obj_get_mtime (BijiItem *note)
 gchar *
 biji_note_obj_get_last_change_date_string (BijiNoteObj *self)
 {
+  g_return_val_if_fail (BIJI_IS_NOTE_OBJ (self), "");
+
   return biji_get_time_diff_with_time (
              biji_note_id_get_mtime (self->priv->id));
 }