#2453 Logging and GUI exception message curtailed by Audio Master active

[Huntley Palmer]

An autopilot.xml caused ( ref tkt2445 ) the error message and runtime error at props.cxx#169 to execute. With F10-File-Sound Configuration Master selected no error message shows, flightgear terminates, GDB shows no backtrace with single stepping control getting lost.
With Audio Master deselected the GUI error message shows before the program terminates and it's possible to step the error condition properly through to props.cxx. Tks