Weird each regression in 2.3.0

[topaxi]

We ran into an issue with the {{#each}} helper after upgrading to 2.3.0.

I'm not 100% sure if it's only happening with DOM File objects but we made a reproducible twiddle here:
https://ember-twiddle.com/9c341eb331bb62b1256b

After selecting files, each filename should appear in the <ul> element. After adding a second one, all previous filenames magically disappear. This worked prior to version 2.3.0 (i.e. 2.2.1).

[mmun]

If you replace

let foobar = [ ...this.get('elements'), event.target.files[0] ]

with

let foobar = [ ...this.get('elements'), { name: event.target.files[0].name } ]

it works fine. I did a bit of digging and it looks like mandatory setter does not work correctly with the File object.

[topaxi]

Thanks, this way we can at least work around this issue for now 👍

[stefanpenner]

#12491 may address this (I believe it is still beta or canary right now)

[mmun]

@stefanpenner You're right. The ember-twiddle works on master and I bisected the fix down to your PR.

[rwjblue]

Demo working against 2.4.0-beta.2: https://ember-twiddle.com/cfca58688d4e6c7f0e2b?openFiles=application.controller.js%2Capplication.template.hbs