I managed to isolate the problem:
window.ToclObject = { bug : 'bug fixed'};
Object.defineProperty(window, 'ToclObject', {});
console.log(window.ToclObject.bug); // error
I also added a fix:
window.ToclObject = { bug : 'bug fixed'};
Object.defineProperty(window, 'ToclObject', { value : window.ToclObject });
console.log(window.ToclObject.bug); // bug fixed
The problem is found here: tocl.base.js:1260
PS: If you're interested in how i isolated it:
I copied your code to a file that shows the problem and removed (deleted) code until the error wouldn't show. Then i backtracked to see what exactly i removed between the error showing and not showing and tada... that's where the problem was.