In the joystick and gamecontroller code, we attempt to fixup SDL_JOYDEVICEADDED/SDL_CONTROLLERDEVICEADDED events if a device is removed prior to the add event being processed by the SDL application.

    num_events = SDL_PeepEvents(events, num_events, SDL_GETEVENT, SDL_JOYDEVICEADDED, SDL_JOYDEVICEADDED);
    for (i = 0; i < num_events; ++i) {
        --events[i].jdevice.which;
    }
    SDL_PeepEvents(events, num_events, SDL_ADDEVENT, 0, 0);

However, there are a couple problems with this fixup logic:
- SDL_JOYDEVICEADDED for joysticks with indexes *lower* than the one removed should not be adjusted
- SDL_JOYDEVICEADDED for the joystick being removed must be removed completely

Due to the above issues, it's possible for SDL applications to receive an invalid device index in their SDL_JOYDEVICEADDED and SDL_CONTROLLERDEVICEADDED events if they aren't pumping events frequently and a joystick is added and removed before they process SDL_JOYDEVICEADDED.