[nautilus] batch-rename-utilities: protect against null error

[Carlos Soriano Sánchez <csoriano src gnome org>]

commit cfa0d2c558f7c0f876f61da771e55caf7002e55c
Author: Carlos Soriano <csoriano gnome org>
Date:   Wed Aug 31 15:14:48 2016 +0200

    batch-rename-utilities: protect against null error
    
    https://bugzilla.gnome.org/show_bug.cgi?id=770586

 src/nautilus-batch-rename-utilities.c |   14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)
---
diff --git a/src/nautilus-batch-rename-utilities.c b/src/nautilus-batch-rename-utilities.c
index 7b4196c..03158c0 100644
--- a/src/nautilus-batch-rename-utilities.c
+++ b/src/nautilus-batch-rename-utilities.c
@@ -745,9 +745,12 @@ on_cursor_callback (GObject      *object,
     success = tracker_sparql_cursor_next_finish (cursor, result, &error);
     if (!success)
     {
-        g_warning ("Error on batch rename tracker query cursor: %s", error->message);
+        if (error)
+        {
+            g_warning ("Error on batch rename tracker query cursor: %s", error->message);
+            g_error_free (error);
+        }
 
-        g_clear_error (&error);
         g_clear_object (&cursor);
 
         nautilus_batch_rename_dialog_query_finished (query_data->dialog,
@@ -1131,8 +1134,11 @@ check_metadata_for_selection (NautilusBatchRenameDialog *dialog,
     connection = tracker_sparql_connection_get (NULL, &error);
     if (!connection)
     {
-        g_warning ("Error on batch rename tracker connection: %s", error->message);
-        g_error_free (error);
+        if (error)
+        {
+            g_warning ("Error on batch rename tracker connection: %s", error->message);
+            g_error_free (error);
+        }
 
         return;
     }