Bug 425756

SUMMARY
On every start of a plasma session, kmixctrl will crash

STEPS TO REPRODUCE
1. Start plasma session
2. Or run kmixctrl directly from a shell
3. 

OBSERVED RESULT
Consistent segmentation faults

EXPECTED RESULT
Manage the audio device

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Yes
(available in About System)
KDE Plasma Version: 5.19.4
KDE Frameworks Version: 5.73.0
Qt Version: 5.14.2

ADDITIONAL INFORMATION
Output of gdb

#0  0x00007ffff20db19e in ?? () from /usr/lib64/pulseaudio/libpulsecommon-13.0.so
#1  0x00007ffff20db248 in pa_socket_client_unref () from /usr/lib64/pulseaudio/libpulsecommon-13.0.so
#2  0x00007ffff5aa4a2a in ?? () from /usr/lib64/libpulse.so.0
#3  0x00007ffff5aa4b42 in ?? () from /usr/lib64/libpulse.so.0
#4  0x00007ffff7bb5b1d in Mixer_PULSE::~Mixer_PULSE (this=0x5555557b7cf0, __in_chrg=<optimized out>)
at /usr/src/debug/kmix-20.08.0-lp152.1.1.x86_64/backends/mixer_pulse.cpp:1073
#5  0x00007ffff7bb5b39 in Mixer_PULSE::~Mixer_PULSE (this=0x5555557b7cf0, __in_chrg=<optimized out>)
at /usr/src/debug/kmix-20.08.0-lp152.1.1.x86_64/backends/mixer_pulse.cpp:1056
#6  0x00007ffff7b8609d in Mixer::~Mixer (this=0x5555557b7c30, __in_chrg=<optimized out>)
at /opt/kde/include/qt5/QtCore/qarraydata.h:236
#7  0x00007ffff7b860b9 in Mixer::~Mixer (this=0x5555557b7c30, __in_chrg=<optimized out>)
at /usr/src/debug/kmix-20.08.0-lp152.1.1.x86_64/core/mixer.cpp:112
#8  0x00007ffff7b7e447 in MixerToolBox::deinitMixer ()
at /usr/src/debug/kmix-20.08.0-lp152.1.1.x86_64/core/mixertoolbox.cpp:356
#9  0x00005555555562c5 in main (argc=<optimized out>, argv=<optimized out>)
at /usr/src/debug/kmix-20.08.0-lp152.1.1.x86_64/apps/kmixctrl.cpp:86