Assign :ref to zero result in missing element in $refs

[Nattapong-sir]

Version

2.5.13

Reproduction link

https://jsfiddle.net/hhu05cd2/18/

Steps to reproduce

Assign any element with ref to 0.
Such as

What is expected?

p exist in $refs

What is actually happening?

p isn't in $refs

---

Workaround is to put additional char to :ref such as

Now, that p will be in this.$refs.

Reference: https://forum.vuejs.org/t/element-with-ref-0-disappear-from-refs/27925

[sqal]

Looks like a bug. Probably this check should be replaced with if (!isDef(key)) return