[evolution] itip_view_rebuild_source_list: Count with parent ESource being NULL

[Milan Crha <mcrha src gnome org>]

commit 118242818d94a67599ee91ba8e0a34d19c4ed367
Author: Milan Crha <mcrha redhat com>
Date:   Thu Feb 18 16:19:11 2021 +0100

    itip_view_rebuild_source_list: Count with parent ESource being NULL
    
    Even this should not normally happen, sometimes the ESource may not
    have its parent, which leads to runtime warnings.

 src/modules/itip-formatter/itip-view.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/src/modules/itip-formatter/itip-view.c b/src/modules/itip-formatter/itip-view.c
index 359d358727..cd93a557f9 100644
--- a/src/modules/itip-formatter/itip-view.c
+++ b/src/modules/itip-formatter/itip-view.c
@@ -1315,20 +1315,21 @@ itip_view_rebuild_source_list (ItipView *view)
        for (link = list; link != NULL; link = g_list_next (link)) {
                ESource *source = E_SOURCE (link->data);
                ESource *parent;
+               const gchar *uid;
 
-               parent = e_source_registry_ref_source (
-                       registry, e_source_get_parent (source));
+               uid = e_source_get_parent (source);
+               parent = uid ? e_source_registry_ref_source (registry, uid) : NULL;
 
                e_web_view_jsc_printf_script_gstring (script,
                        "EvoItip.AddToSourceList(%s, %s, %s, %s, %s, %x);",
                        view->priv->part_id,
-                       e_source_get_uid (parent),
-                       e_source_get_display_name (parent),
+                       parent ? e_source_get_uid (parent) : "",
+                       parent ? e_source_get_display_name (parent) : "",
                        e_source_get_uid (source),
                        e_source_get_display_name (source),
                        e_source_get_writable (source));
 
-               g_object_unref (parent);
+               g_clear_object (&parent);
        }
 
        e_web_view_jsc_run_script_take (WEBKIT_WEB_VIEW (web_view), g_string_free (script, FALSE),