init: Fix initialisation crash

Fix a case where initialisation fails without setting
the passed-in GError and the caller assumes it will be
set, and add a guard to catch the condition in case it
happens again in the future.

Part-of: <!217>

ges/ges.c

@@ -120,6 +120,9 @@ ges_init_post (GOptionContext * context, GOptionGroup * group, gpointer data,
   _init_formatter_assets ();
   if (!_ges_uri_asset_ensure_setup (uriasset_klass)) {
     GST_ERROR ("cannot setup uri asset");
+    if (error)
+      *error = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_MISSING_PLUGIN,
+          "Cannot initialize URI asset class.");
     goto failed;
   }
 

tools/ges-launcher.c

@@ -1051,9 +1051,13 @@ _local_command_line (GApplication * application, gchar ** arguments[],
   gst_init (&argc, arguments);
   if (!ges_launcher_parse_options (self, arguments, &argc, ctx, &error)) {
     gst_init (NULL, NULL);
-    ges_printerr ("Error initializing: %s\n", error->message);
     g_option_context_free (ctx);
-    g_error_free (error);
+    if (error) {
+      ges_printerr ("Error initializing: %s\n", error->message);
+      g_error_free (error);
+    } else {
+      ges_printerr ("Error parsing command line arguments\n");
+    }
     *exit_status = 1;
     goto done;
   }