[gnome-software] trivial: Fix crash when loading flatpakref files

[Richard Hughes <rhughes src gnome org>]

commit 9ccbc3472bdfe2864bbd64b9d01484c680f4a141
Author: Richard Hughes <richard hughsie com>
Date:   Tue Jul 11 20:19:31 2017 +0100

    trivial: Fix crash when loading flatpakref files

 plugins/flatpak/gs-plugin-flatpak.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/plugins/flatpak/gs-plugin-flatpak.c b/plugins/flatpak/gs-plugin-flatpak.c
index 0639222..77a0012 100644
--- a/plugins/flatpak/gs-plugin-flatpak.c
+++ b/plugins/flatpak/gs-plugin-flatpak.c
@@ -634,7 +634,7 @@ gs_plugin_flatpak_file_to_app_ref (GsPlugin *plugin,
        runtime_app = gs_app_get_runtime (app_tmp);
        if (runtime_app != NULL &&
            gs_app_get_state (runtime_app) != AS_APP_STATE_INSTALLED) {
-               g_autoptr(GsAppList) list_system_runtimes = NULL;
+               g_autoptr(GsAppList) list_system_runtimes = gs_app_list_new ();
                for (guint i = 0; i < priv->flatpaks->len; i++) {
                        GsFlatpak *flatpak = g_ptr_array_index (priv->flatpaks, i);
                        if (gs_flatpak_get_flags (flatpak) & GS_FLATPAK_FLAG_IS_TEMPORARY)