segfault after changing audio api

This requires a current revision of purr-data capable of remembering preferences in the user.settings file. To reproduce:

  1. Make sure that ~/.pd-l2ork exists (create if necessary) so that preferences are remembered across invocations.

  2. Launch pd-l2ork and go to the preferences dialog. Change the audio api, e.g., from the default ALSA to Jack. Press Ok.

  3. Exit pd-l2ork. ~/.pd-l2ork/user.settings should exist now.

  4. Relaunch pd-l2ork => pd-l2ork dumps core with a segmentation fault.

gdb backtrace:

#0  0x00000000004a3df4 in ?? ()
#1  0x00000000004a42c2 in gui_do_vmess ()
#2  0x00000000004a43dc in gui_vmess ()
#3  0x00000000004a250c in sys_main ()
#4  0x00007ffff63ba291 in __libc_start_main () from /usr/lib/libc.so.6
#5  0x0000000000417c9a in _start ()

I can reproduce this 100% on Arch, using the latest revision from today. Doesn't matter whether jack is actually running or not. Mainline pd-l2ork doesn't exhibit this behaviour.