The same is happening to me using V4L2 Webcam and Focus simulator.
As soon as I increase exposure and select a different field, for example, the ccd detector, it crashes Kstars, where's the gdb debug:
nmac@AstroPC:~$ gdb kstars
GNU gdb (Ubuntu 7.12.50.20170314-0ubuntu1.1) 7.12.50.20170314-git
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <
gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<
www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<
www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from kstars...Reading symbols from /usr/lib/debug//usr/bin/kstars...done.
done.
(gdb) run
Starting program: /usr/bin/kstars
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffdff59700 (LWP 6596)]
[New Thread 0x7fffde6e1700 (LWP 6600)]
[New Thread 0x7fffd7fff700 (LWP 6604)]
[New Thread 0x7fffd77fe700 (LWP 6605)]
[New Thread 0x7fffd63e3700 (LWP 6612)]
[New Thread 0x7fffc3fff700 (LWP 6641)]
Thread 1 "kstars" received signal SIGSEGV, Segmentation fault.
QString::QString (other=..., this=0x7fffffffcb48) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qstring.h:901
901 /usr/include/x86_64-linux-gnu/qt5/QtCore/qstring.h: No such file or directory.
(gdb)
Attached I send the Kstars log: