[epiphany] sync-service: Handle the case when secret_item_get_secret() returns NULL

[Gabriel Ivașcu <gabrielivascu src gnome org>]

commit 7963315fd3ac3bc30308ade3d9d8896fed3516da
Author: Gabriel Ivascu <gabrielivascu gnome org>
Date:   Tue Sep 26 01:23:06 2017 +0300

    sync-service: Handle the case when secret_item_get_secret() returns NULL
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788140

 lib/sync/ephy-sync-service.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/lib/sync/ephy-sync-service.c b/lib/sync/ephy-sync-service.c
index 02f25de..3501363 100644
--- a/lib/sync/ephy-sync-service.c
+++ b/lib/sync/ephy-sync-service.c
@@ -1458,6 +1458,12 @@ load_secrets_cb (SecretService   *service,
   }
 
   value = secret_item_get_secret ((SecretItem *)res->data);
+  if (!value) {
+    g_warning ("Failed to retrieve the value of the sync secrets");
+    message = _("The sync secrets for the current sync user are invalid.");
+    goto out_error;
+  }
+
   node = json_from_string (secret_value_get_text (value), &error);
   if (error) {
     g_warning ("Sync secrets are not a valid JSON: %s", error->message);