Segmentation fault (core dumped) during gracefull shutdown

This is the code that causes segmentation fault during gracefull shutdown that I'm trying to do https://github.com/TwistedScorpio/OTHire/blob/master/source/game.cpp#L144 Can any1 help me fix this? Expecting no segfault when doing gracefull shutdown.

gdb log:
gdb) bt full
#0  0x00000000 in ?? ()
No symbol table info available.
#1  0xf6e0d04d in std::ostream::flush() ()
   from /usr/lib/i386-linux-gnu/libstdc++.so.6
No symbol table info available.
#2  0xf6d99614 in std::ios_base::Init::~Init() ()
   from /usr/lib/i386-linux-gnu/libstdc++.so.6
No symbol table info available.
#3  0xf6b19b2a in __cxa_finalize () from /lib/i386-linux-gnu/libc.so.6
No symbol table info available.
#4  0xf7260b83 in ?? ()
   from /usr/lib/i386-linux-gnu/libboost_date_time.so.1.62.0
No symbol table info available.
#5  0xf77af142 in ?? () from /lib/ld-linux.so.2
No symbol table info available.
#6  0xf6b197ab in ?? () from /lib/i386-linux-gnu/libc.so.6
No symbol table info available.
#7  0xf6b19811 in exit () from /lib/i386-linux-gnu/libc.so.6
No symbol table info available.
#8  0xf6b03292 in __libc_start_main () from /lib/i386-linux-gnu/libc.so.6
No symbol table info available.
#9  0x568159b1 in _start ()
No symbol table info available.