Hello,

I apologise in advance for the scant details in this bug report; I'd appreciate
any assistance in the debugging process.

I've been building from the emacs-27 branch for the last six months or so. My
next-to-last build was probably a week or two ago. Upon the announcement of
27.0.90 pre-test I built Emacs again, and with this build I'm experiencing
perplexing crashes of Emacs.app.

I have attached the three most recent crash reports.

The crashes have no discernible pattern, except that they occur more often when
task-switching to Emacs.app from another macOS app, e.g. this morning, after
leaving Emacs open last night, I switched to Emacs.app and had an immediate
crash.