Pharo had the same problem, which users report as successfully fixed.
However the last response I see says...
> he has to copy it into /Applications because otherwise Sierra copy it into a sandbox (then it does not find sources).

You can search  'Sierra' on forum.world.st for more info.

cheers -ben

On Tue, Oct 11, 2016 at 1:13 AM, glenpaling <slp5591 at me.com> wrote:
> I foolishly updated my Macs to the latest OS (Sierra) without checking for
> compatibility with Squeak. No recent (all Cog?) VMs will work. The VM
> launches but no window appears. The problem appears to be addressed in
> OpenSmalltalk macOS Sierra Support issue #39
> (https://github.com/OpenSmalltalk/opensmalltalk-vm/issues/39). It's marked
> as 'Closed'. Are there plans to include this fix in the official Squeak
> release?
>
> I see that I can download and build my own VM from the Open Smalltalk site
> but I've never done this before, it looks a little ominous....
>
> Perhaps a note in Squeak News and on the Squeak website would help to warn
> other users that they will not be able to run Squeak if they upgrade their
> OS.
>
> Glen
>
>
>
> --
> View this message in context: http://forum.world.st/Squeak-Does-Not-Run-on-MAC-OS-Sierra-tp4918570.html
> Sent from the Squeak - Dev mailing list archive at Nabble.com.
>