[libgda] Check vcnc: fixed warning

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 68b389ce30633a0266b966d0ed6afb53e6635d80
Author: Daniel Espinosa <esodan gmail com>
Date:   Thu Apr 4 13:47:13 2019 -0600

    Check vcnc: fixed warning

 tests/data-models/check_vcnc.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)
---
diff --git a/tests/data-models/check_vcnc.c b/tests/data-models/check_vcnc.c
index 008ab8ee9..e5c7564fa 100644
--- a/tests/data-models/check_vcnc.c
+++ b/tests/data-models/check_vcnc.c
@@ -705,26 +705,31 @@ test_multiple_threads (GThreadFunc func, GdaConnection *virtual)
 
 /* executed in another thread */
 gpointer
-threads_select_random_start_thread (ThData *data, GError **error)
+threads_select_random_start_thread (ThData *data)
 {
        GdaDataModel *model;
        GdaDataModel *ref;
        GdaDataModelIter *iter;
        GThread *self;
        gchar *str;
+  GError *error = NULL;
 
        self = g_thread_self ();
        g_message ("*** sub thread %p SELECT RANDOM\n", self);
        model = run_sql_select (data->virtual, "SELECT * FROM countries WHERE code LIKE 'A%' ORDER BY code",
-                               FALSE, error);
+                               FALSE, &error);
        if (!model) {
-               g_message ("Could not execute SELECT with forward iter only");
+               g_message ("Could not execute SELECT with forward iter only: %s",
+               error != NULL && error->message != NULL ? error->message : "No Datail");
+    g_clear_error (&error);
                return NULL;
        }
 
        ref = load_from_file ("countriesA.xml");
-       if (!assert_data_model_equal (model, ref, error)) {
-               g_message ("Error: equal model vs ref");
+       if (!assert_data_model_equal (model, ref, &error)) {
+               g_message ("Error: equal model vs ref %s",
+               error != NULL && error->message != NULL ? error->message : "No Datail");
+    g_clear_error (&error);
                return NULL;
        }