To turn debug logging on, set onmount.debug to true.
onmount.debug = true
If you'd like to do this automatically, you can turn it on by a secret flag:
onmount.debug = (window.localStorage &&
window.localStorage['onmount_debug'] &&
true)
You can turn it on in your JavaScript console by typing localStorage.onmount_debug = true, and turn it off with delete localStorage.onmount_debug.