Xcodeのplaygroundだとこうなので
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT) * frame #0: 0x00007fffaba7aa9b libobjc.A.dylib`_objc_msgSend_uncached + 11 frame #1: 0x00007fff9865d231 Foundation`-[NSPlaceholderString initWithString:] + 107 frame #2: 0x00000001036ca007 PlaygroundLogger`function signature specialization <Arg[0] = Dead> of static PlaygroundLogger.LoggingPolicyStack.get() -> PlaygroundLogger.LoggingPolicyStack + 151 frame #3: 0x00000001036c3f22 PlaygroundLogger`function signature specialization <Arg[1] = Owned To Guaranteed and Exploded> of playground_log_hidden + 98 frame #4: 0x00000001036c365b PlaygroundLogger`playground_log_hidden + 27 frame #5: 0x00000001041db0a7 $__lldb_expr158`Never.init(nilLiteral=() @ scalar) at MyPlayground.playground:4