[gnome-software] trivial: Add a g_return_val_if_fail() to help debug an issue

[Richard Hughes <rhughes src gnome org>]

commit e0d8ad7cc872a80cd29e9bafcf3803153f823c00
Author: Richard Hughes <richard hughsie com>
Date:   Wed Jun 1 09:44:16 2016 +0100

    trivial: Add a g_return_val_if_fail() to help debug an issue

 src/plugins/packagekit-common.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/plugins/packagekit-common.c b/src/plugins/packagekit-common.c
index 9709f22..af04a4d 100644
--- a/src/plugins/packagekit-common.c
+++ b/src/plugins/packagekit-common.c
@@ -189,6 +189,9 @@ gs_plugin_packagekit_add_results (GsPlugin *plugin,
        g_autoptr(GPtrArray) array_filtered = NULL;
        g_autoptr(GPtrArray) array = NULL;
 
+       g_return_val_if_fail (GS_IS_PLUGIN (plugin), FALSE);
+       g_return_val_if_fail (GS_IS_APP_LIST (list), FALSE);
+
        /* check error code */
        error_code = pk_results_get_error_code (results);
        if (error_code != NULL) {