Uncaught TypeError: Cannot read property 'update' of undefined

[fullfs]

The error points to the code

p.notify = function () {
  for (var i = 0, l = this.subs.length; i < l; i++) {
    this.subs[i].update()
  }
}

The problem occurs at the setting a big amount of data to a single property (this.offer = offer) in a complex component.
Can't reproduce it in fiddle, but it looks like subs array changes its length while iterating it in notify.

Giving up on saving up subs length fixes the problem:

for (var i = 0; i < this.subs.length; i++) {

[bdaglish]

I've had this a couple of times, but it seems to be when there's a watched/referenced property that isn't originally specified in the data {} section. Adding the property usually cures it.

[anfinil]

This issue also repeats if you try to nullify some data property that was bind several times. For example,

<div v-if='customer'>
  <div v-show='customer'>{{customer.id}}</div>
  <div v-show='customer'>{{customer.name}}</div>
</div>

When you try to set customer to null it will raise error because this.subs.length will be 3. But after first this.subs[i].update() run it will modify this.stubs and it will raise error on next loop.

[anfinil]

Changing to for (var i = 0; i < this.subs.length; i++) { fixes the problem.