[gnome-software] trivial: Add tiny assert to shut up coverity

[Richard Hughes <rhughes src gnome org>]

commit 569ebedfc3f7cae0d762639c860871734ad2e8a7
Author: Richard Hughes <richard hughsie com>
Date:   Thu Dec 15 13:32:35 2016 +0000

    trivial: Add tiny assert to shut up coverity

 src/gs-plugin-loader.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/gs-plugin-loader.c b/src/gs-plugin-loader.c
index 3a034ab..0912e41 100644
--- a/src/gs-plugin-loader.c
+++ b/src/gs-plugin-loader.c
@@ -4480,6 +4480,7 @@ gs_plugin_loader_update_thread_cb (GTask *task,
                                                                             app,
                                                                             apps->len,
                                                                             k);
+                                       g_assert (helper != NULL);
                                }
 
                                ptask = as_profile_start (priv->profile,