If key is zero it doesn't show up in the component tree

[AnwarElbo]

Version

5.0.0-beta.3

Browser and OS info

Chrome Version 70.0.3538.102, Windows 10

Steps to reproduce

Set key to 0 of a component you won't see it back in vue devtools, this occurs if you put the index of an array as the key which starts at 0. The first one is invisible after that one the 1 etc. is visible.

What is expected?

That it also shows 0 as a valid key

What is actually happening?

It doesnt show up in the component tree

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Already fixed the bug I will set up a pull request :)!