[grilo-plugins/sam/fix-no-chromaprint-crash] tracker: Guard against invalid key mappings

[Sam Thursfield <sthursfield src gnome org>]

commit 6d66bbd54e6c3a1edef63c031c39e52cd647cc05
Author: Sam Thursfield <sam afuera me uk>
Date:   Sun Sep 29 18:03:38 2019 +0200

    tracker: Guard against invalid key mappings
    
    Any future mistakes like https://gitlab.gnome.org/GNOME/grilo-plugins/issues/61
    will not crash the process but will just trigger a g_warning() message.

 src/tracker/grl-tracker-utils.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/tracker/grl-tracker-utils.c b/src/tracker/grl-tracker-utils.c
index 406f4efc..d80e5133 100644
--- a/src/tracker/grl-tracker-utils.c
+++ b/src/tracker/grl-tracker-utils.c
@@ -157,6 +157,8 @@ insert_key_mapping (GrlKeyID     grl_key,
                     const gchar *sparql_key_attr_call,
                     const gchar *sparql_key_flavor)
 {
+  g_return_val_if_fail (grl_key != GRL_METADATA_KEY_INVALID, NULL);
+
   tracker_grl_sparql_t *assoc = g_new0 (tracker_grl_sparql_t, 1);
   GList *assoc_list = g_hash_table_lookup (grl_to_sparql_mapping,
                                            GRLKEYID_TO_POINTER (grl_key));