crashing in org.gnu.Emacs in deliver_fatal_thread_signal • Uncaught Exception 'NSInternalInconsistencyException': nextEventMatchingMask should only be called from the Main Thread!terminating with uncaught exception of type NSException : at com.apple.AppKit in -[NSApplication(NSEvent) shouldBeTreatedAsInkEvent:] + 0
Apparently, calling nextEventMatchingMask from a background thread is risky, and this has been made an assert as on 10.12, hence the crash.