Whenever i search a message in Kmail program completely crashes.

<code>
terminate called after throwing an instance of 'std::logic_error'
  what():  basic_string::_S_construct null not valid
Received signal 6
#0 0x7f505e87ccb7 <unknown>
#1 0x7f505d62949e <unknown>
#2 0x7f505e87d04d <unknown>
#3 0x7f507358b940 <unknown>
#4 0x7f507358b8c7 __GI_raise
#5 0x7f507358cc9a __GI_abort
#6 0x7f50739912e5 __gnu_cxx::__verbose_terminate_handler()
#7 0x7f507398f0d6 <unknown>
#8 0x7f507398f121 std::terminate()
#9 0x7f507398f363 __cxa_throw
#10 0x7f50739b7b6f std::__throw_logic_error()
#11 0x7f50739d1c69 std::string::_S_construct<>()
#12 0x7f50739d200c std::string::string()
#13 0x7f506e1b4e31 Akonadi::Search::PIM::EmailQuery::exec()
#14 0x7f50720d2586 <unknown>
#15 0x7f507211e66f <unknown>
#16 0x7f5073f20a83 QMetaObject::activate()
#17 0x7f5073f2dad7 QTimer::timeout()
#18 0x7f5073f2ddb2 QTimer::timerEvent()
#19 0x7f5073f21af4 QObject::event()
#20 0x7f5074c0371c QApplicationPrivate::notify_helper()
#21 0x7f5074c0a500 QApplication::notify()
#22 0x7f5073ef6115 QCoreApplication::notifyInternal2()
#23 0x7f5073f4841e QTimerInfoList::activateTimers()
#24 0x7f5073f48a61 <unknown>
#25 0x7f506749f134 g_main_context_dispatch
#26 0x7f506749f388 <unknown>
#27 0x7f506749f42c g_main_context_iteration
#28 0x7f5073f48d8c QEventDispatcherGlib::processEvents()
#29 0x7f5047461c91 <unknown>
#30 0x7f5073ef483b QEventLoop::exec()
#31 0x7f5073efcef4 QCoreApplication::exec()
#32 0x0000004037b0 <unknown>
#33 0x7f50735776d5 __libc_start_main
#34 0x000000403989 _start
  r8: 000000000000000a  r9: 00007f50764d4980 r10: 0000000000000008 r11: 0000000000000206
 r12: 000000000688b490 r13: 00007fff21797a30 r14: 00007fff21797a10 r15: 00007fff21797a50
  di: 0000000000002850  si: 0000000000002850  bp: 00007f50738f36d8  bx: 00000000023990b8
  dx: 0000000000000006  ax: 0000000000000000  cx: 00007f507358b8c7  sp: 00007fff217971b8
  ip: 00007f507358b8c7 efl: 0000000000000206 cgf: 0000000000000033 erf: 0000000000000000
 trp: 0000000000000000 msk: 0000000000000000 cr2: 0000000000000000
[end of stack trace]
Calling _exit(1). Core file will not be generated.
</code>

Thanks