Bug#858283: gsequencer: GSequencer crashes as no soundcard configured

[Joël Krähemann]

Source: gsequencer
Version: 0.7.122-2
Severity: important

Dear Maintainer,

GSequencer allows configuration in place. As removing all soundcards and
adding certain machines it does SIGSEGV. This happens because of a NULL
pointer dereference.

GSequencer shall not crash under any circumstances.

-- System Information:
Debian Release: 9.0
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-1-rt-amd64 (SMP w/24 CPU cores; PREEMPT)
Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)