[evolution-data-server] Fix a crash in server_side_source_credentials_lookup_cb()

[Milan Crha <mcrha src gnome org>]

commit 5677aadad595aaa254f205053e447fee8c166b6e
Author: Milan Crha <mcrha redhat com>
Date:   Fri Feb 27 07:57:17 2015 +0100

    Fix a crash in server_side_source_credentials_lookup_cb()
    
    A NULL 'error' variable dereference caused the crash. The change
    also cleanups the code a bit, by removing incorrect runtime checks.

 libebackend/e-server-side-source.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/libebackend/e-server-side-source.c b/libebackend/e-server-side-source.c
index 8e3213e..c47e82c 100644
--- a/libebackend/e-server-side-source.c
+++ b/libebackend/e-server-side-source.c
@@ -406,7 +406,6 @@ server_side_source_credentials_lookup_cb (GObject *source_object,
        dbus_object = e_source_ref_dbus_object (E_SOURCE (data->source));
        if (!dbus_object) {
                e_named_parameters_free (credentials);
-               g_warn_if_fail (dbus_object != NULL);
                reinvoke_credentials_required_data_free (data);
                return;
        }
@@ -414,8 +413,7 @@ server_side_source_credentials_lookup_cb (GObject *source_object,
        dbus_source = e_dbus_object_get_source (E_DBUS_OBJECT (dbus_object));
        if (!dbus_source) {
                e_named_parameters_free (credentials);
-               g_warn_if_fail (dbus_source != NULL);
-               g_object_unref (dbus_object);
+               g_clear_object (&dbus_object);
                reinvoke_credentials_required_data_free (data);
                return;
        }
@@ -463,6 +461,9 @@ server_side_source_credentials_lookup_cb (GObject *source_object,
                        arg_dbus_error_message = data->arg_dbus_error_message;
 
                        if (!arg_dbus_error_name || !*arg_dbus_error_name) {
+                               if (!error)
+                                       error = g_error_new_literal (G_IO_ERROR, G_IO_ERROR_FAILED, 
_("Unknown error"));
+
                                dbus_error_name = g_dbus_error_encode_gerror (error);
                                arg_dbus_error_name = dbus_error_name;
                                arg_dbus_error_message = error->message;