[gnome-shell/wip/carlosg/osk-emoji-and-keypad: 17/22] keyboard: Fix JS warning

[Carlos Garnacho <carlosg src gnome org>]

commit 24fc6596a95d4ad7d675556445660711a2d5fdfa
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Jan 21 21:40:59 2019 +0100

    keyboard: Fix JS warning
    
    The label field may be empty here (eg. buttons fully styled through css),
    just resort to an empty string then.

 js/ui/keyboard.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/ui/keyboard.js b/js/ui/keyboard.js
index c58ab81e4..354544bd6 100644
--- a/js/ui/keyboard.js
+++ b/js/ui/keyboard.js
@@ -818,7 +818,7 @@ var Keyboard = new Lang.Class({
             let switchToLevel = key.level;
             let action = key.action;
 
-            extraButton = new Key(key.label, []);
+            extraButton = new Key(key.label || '', []);
 
             extraButton.keyButton.add_style_class_name('default-key');
             if (key.extraClassName != null)