Component block array iteration -- You modified XXX twice in a single render

[Samsinite]

Hi Guys,

I have a set of calendar components that I've put together in an application that loop over sets of data and render the component block using values in those sets. Was hoping to see a really nice speed bump when updating to canary, but instead I am getting a You modified XXX twice in a single render warning along with the app crashing and locking my browser on a re-render.

It can be reproduced using the example app I've put together here by clicking on the prev/next buttons. I would suggest opening the chrome inspector first before clicking a button as I have to force quit or pause the execution because it gets stuck in a loop spitting out warnings.

[sandstrom]

This discussion may be helpful: #11156

Edit: yes I know it's another root cause/issue, but the error is the same. I thought it may help you in understanding what may be causing your problem. Also, a suggestion is to keep the issue succinct, and update/edit it instead of posting a stream of consciousness with comments.

[Samsinite]

@sandstrom not really, a completely different issue. There is no elementId modification going on.

Edit: Looks like the issue goes away if I pass a POJO instead of null or a number.

[Samsinite]

Closing in favor of #11519 which has an attached JSBin as well.