the claculator example crashes

[mattetti]

Thread 0 Crashed: Dispatch queue: com.apple.main-thread
0 libobjc.A.dylib 0x00007fff87cb311c objc_msgSend + 40
1 libmacruby.dylib 0x00000001000bc280 rb_reg_search2 + 144 (re.c:1490)
2 libmacruby.dylib 0x00000001000f49ed str_gsub + 157 (string.c:2059)
3 libmacruby.dylib 0x0000000100171952 rb_vm_dispatch + 7010 (dispatcher.cpp:433)
4 ??? 0x0000000101113a71 0 + 4312873585

Thread 1: Dispatch queue: com.apple.libdispatch-manager
0 libSystem.B.dylib 0x00007fff88520bba kevent + 10
1 libSystem.B.dylib 0x00007fff88522a85 _dispatch_mgr_invoke + 154
2 libSystem.B.dylib 0x00007fff8852275c _dispatch_queue_invoke + 185
3 libSystem.B.dylib 0x00007fff88522286 _dispatch_worker_thread2 + 244
4 libSystem.B.dylib 0x00007fff88521bb8 _pthread_wqthread + 353
5 libSystem.B.dylib 0x00007fff88521a55 start_wqthread + 13

Thread 2:
0 libSystem.B.dylib 0x00007fff885219da __workq_kernreturn + 10
1 libSystem.B.dylib 0x00007fff88521dec _pthread_wqthread + 917
2 libSystem.B.dylib 0x00007fff88521a55 start_wqthread + 13