exception thrown on process exit (`checkStatus()` callfails)

[christianparpart]

stack trace in question

Thread 6 Crashed:: Terminal.Loop
0   ???                                 0x7ff8a1d0ea78 ???
1   libsystem_kernel.dylib              0x7ff8118207ce __pthread_kill + 10
2   libsystem_pthread.dylib             0x7ff811858f30 pthread_kill + 262
3   libsystem_c.dylib                   0x7ff811777a49 abort + 126
4   libc++abi.dylib                     0x7ff811811c72 abort_message + 241
5   libc++abi.dylib                     0x7ff811803e00 demangling_terminate_handler() + 240
6   libobjc.A.dylib                     0x7ff8114a4673 _objc_terminate() + 104
7   libc++abi.dylib                     0x7ff8118110cb std::__terminate(void (*)()) + 6
8   libc++abi.dylib                     0x7ff811813a97 __cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception*) + 27
9   libc++abi.dylib                     0x7ff811813a5e __cxa_throw + 116
10  contour                                0x1022f8ba1 vtpty::Process::Private::checkStatus(bool) const + 481
11  contour                                0x1021fa791 contour::TerminalSession::onClosed() + 353
12  contour                                0x1021f809a contour::TerminalSession::mainLoop() + 506
13  contour                                0x1022097e3 void* std::__1::__thread_proxy[abi:v15006]<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct>>, std::__1::__bind<void (contour::TerminalSession::*)(), contour::TerminalSession*>>>(void*) + 67
14  libsystem_pthread.dylib             0x7ff811859202 _pthread_start + 99
15  libsystem_pthread.dylib             0x7ff811854bab thread_start + 15

I remember we had that problem in the past already. It maybe is a synchronization issue.