Prevent error

editor/js/Editor.js

@@ -482,7 +482,11 @@ Editor.prototype = {
 
 	focus: function ( object ) {
 
-		this.signals.objectFocused.dispatch( object );
+		if ( object !== undefined ) {
+
+			this.signals.objectFocused.dispatch( object );
+
+		}
 
 	},