I am building a permissions UI, I have a list of permissions with a select list next to each permission. The permissions are represented by an observable array of objects which
I had a similar problem and I just modified the event handler to check the type of the variable. The type is only set after the user selects a value, not when the page is first loaded.
self.permissionChanged = function (l) {
if (typeof l != 'undefined') {
...
}
}