Comment 0 for bug 1668466

When right clicking in GTK apps, Mir servers often crash with:

terminate called after throwing an instance of 'std::out_of_range'
  what(): map::at

Thread 6 "Mir/IPC" received signal SIGABRT, Aborted.
[Switching to Thread 0x7fffe7fff700 (LWP 24062)]
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:58
58 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:58
#1 0x00007ffff7a483ea in __GI_abort () at abort.c:89
#2 0x00007ffff632156d in __gnu_cxx::__verbose_terminate_handler() ()
   from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#3 0x00007ffff631f316 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#4 0x00007ffff631e2a9 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#5 0x00007ffff631ec5d in __gxx_personality_v0 ()
   from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6 0x00007ffff5d7ff43 in ?? () from /lib/x86_64-linux-gnu/libgcc_s.so.1
#7 0x00007ffff5d80447 in _Unwind_Resume ()
   from /lib/x86_64-linux-gnu/libgcc_s.so.1
#8 0x00007ffff773c802 in ?? ()
   from /usr/lib/x86_64-linux-gnu/libmirserver.so.43
#9 0x00007ffff7717ab9 in ?? ()

Sounds similar to bug 1656727.