[gnome-shell] realmd: Set login format to null on start and update if invalid

[Florian Müllner <fmuellner src gnome org>]

commit ea5aaa8ab2e386b59cd28f1266d4712194c97dcc
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Thu May 23 06:12:56 2019 +0200

    realmd: Set login format to null on start and update if invalid
    
    We were checking an undefined property but that would lead to a a warning.
    Instead we can consider the login format unset until is null, and in case
    update it.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/700

 js/gdm/realmd.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/js/gdm/realmd.js b/js/gdm/realmd.js
index 913fdd3bef..7584968209 100644
--- a/js/gdm/realmd.js
+++ b/js/gdm/realmd.js
@@ -21,6 +21,7 @@ var Manager = class {
                                            '/org/freedesktop/realmd',
                                            this._reloadRealms.bind(this));
         this._realms = {};
+        this._loginFormat = null;
 
         this._signalId = this._aggregateProvider.connect('g-properties-changed',
             (proxy, properties) => {
@@ -86,7 +87,7 @@ var Manager = class {
     }
 
     get loginFormat() {
-        if (this._loginFormat !== undefined)
+        if (this._loginFormat)
             return this._loginFormat;
 
         this._updateLoginFormat();