expression inside "v-if" block turning false with transition

Chrome 47, Vue v1.0.13 [In this fiddle](https://jsfiddle.net/4Ltf5n89/8/).
To click the button will meet error (see it in console). But it is OK [without transition](https://jsfiddle.net/4Ltf5n89/9/).
I wonder about if the expression should be evaluated when transition leaves since "v-if" become a false value?
