[gnome-calendar] manager: fail when client unit isn't found

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 1362762efe5a68174f97293da6f30e450c51c837
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Apr 13 07:08:35 2017 -0300

    manager: fail when client unit isn't found
    
    This is a temporary solution to avoid a crash that
    some people are experiencing. More investigation is
    required.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781071

 src/gcal-manager.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/gcal-manager.c b/src/gcal-manager.c
index 91587b1..cf4995f 100644
--- a/src/gcal-manager.c
+++ b/src/gcal-manager.c
@@ -1716,6 +1716,8 @@ gcal_manager_create_event (GcalManager *manager,
   component = gcal_event_get_component (event);
   unit = g_hash_table_lookup (manager->clients, source);
 
+  g_return_if_fail (unit != NULL);
+
   new_event_icalcomp = e_cal_component_get_icalcomponent (component);
 
   data = g_new0 (AsyncOpsData, 1);