CocoaLumberjack: Crash DDLog.m line 839 - [DDLog lt_log:]

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Issue Info

### Stack:
cocoa.lumberjack
0  libsystem_kernel.dylib         0x1a85539fc __ulock_wait + 8
1  libdispatch.dylib              0x1a8397238 _dispatch_ulock_wait + 56
2  libdispatch.dylib              0x1a8397c38 _dispatch_group_wait_slow + 40
3  CocoaLumberjack                0x104adae78 -[DDLog lt_log:] + 839 (DDLog.m:839)
4  CocoaLumberjack                0x104ad962c __40-[DDLog queueLogMessage:asynchronously:]_block_invoke + 358 (DDLog.m:358)
5  libdispatch.dylib              0x1a83f56c8 _dispatch_call_block_and_release + 24
6  libdispatch.dylib              0x1a83f6484 _dispatch_client_callout + 16
7  libdispatch.dylib              0x1a839dbd0 _dispatch_lane_serial_drain$VARIANT$mp + 592
8  libdispatch.dylib              0x1a839e718 _dispatch_lane_invoke$VARIANT$mp + 432
9  libdispatch.dylib              0x1a83a6eb8 _dispatch_workloop_worker_thread + 600
10 libsystem_pthread.dylib        0x1a85d90dc _pthread_wqthread + 312
11 libsystem_pthread.dylib        0x1a85dbcec start_wqthread + 4