Hardware signals, PtAppAddSignalProc(), program lockup

Setup: A Photon app that uses PtAppAddSignalProc() to add a handler for some
signals, including SIGFPE and SIGSEGV for hardware-generated errors. The app
has a debug menu that allows me to cause

The Problem: When a hardware-generated error occurs – e.g., division by
zero, NULL pointer assignment – the app locks up.