keyboard: Check monitor validity before deferencing it

Monitor could be invalid in headless mode.

https://bugzilla.gnome.org/show_bug.cgi?id=788882

diff --git a/js/ui/keyboard.js b/js/ui/keyboard.js
index 96da88781c5fdb3aa9ba29f6397c860239838c5a..3087cefa5585299f69be428cfa62cd24404eb59c 100644 (file)
--- a/js/ui/keyboard.js
+++ b/js/ui/keyboard.js
@@ -1148,7 +1148,7 @@ var Keyboard = new Lang.Class({
             let windowActor = window.get_compositor_private();
             let delta = 0;
 
-            if (frameRect.y + y + h >= monitor.height - keyboardHeight)
+            if (monitor && frameRect.y + y + h >= monitor.height - keyboardHeight)
                 delta = keyboardHeight;
 
             this._animateWindow(window, true, delta);