"Try it yourself" not working for two examples in "Object Protection" tutorial page

[Ilan]

JavaScript Object Protection : https://www.w3schools.com/js/js_object_protection.asp (I think this page is recently added?)

For the sub-topic "JavaScript Object.isExtensible()", two links from 3rd and 4th example links give errors : "The file you asked for does not exist".

     3rd Example : https://www.w3schools.com/js/tryit.asp?filename=tryjsref_object_isextensible

     4th Example : https://www.w3schools.com/js/tryit.asp?filename=tryjsref_object_isextensible2

Also, is it just me? Some times the arrow keys and enter key stop working when typing in forum topics/posts.