I'm late to the party but I just tested your CL (from Oct 20th).
Unfortunately it doesn't work, the stack traces are wrong, both in case of a Panic and in case of a nil pointer.
# Crashlytics - plaintext stacktrace downloaded by Steeve Morin at Tue, 14 Nov 2017 00:27:19 GMT
# Platform: ios
# Application: testapp-swift
# Version: 1.0 (1)
# Issue #: 2
# Issue ID: 591c99d0be077a4dccdaf367
# Session ID: 5a402e3c98264061900ece2494bd61b6_72788d9ac8d211e78fd856847afe9799_0_v2
# Date: 2017-11-14T00:26:00Z
# OS Version: 11.1.1 (15B150)
# Device: iPhone X
# RAM Free: 6.8%
# Disk Free: 69.1%
#0. Crashed: com.apple.main-thread
0 testapp-swift 0x1046b9578 runtime.raiseproc + 24
1 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
2 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
3 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
4 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
5 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
6 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
7 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
8 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
9 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
10 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
--
#0. Crashed: com.apple.main-thread
0 testapp-swift 0x1046b9578 runtime.raiseproc + 24
1 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
2 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
3 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
4 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
5 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
6 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
7 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
8 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
9 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
10 testapp-swift 0x1046a5aa0 runtime.dieFromSignal + 64
#1. Thread
0 testapp-swift 0x1046b990c runtime.mach_semaphore_wait + 12
1 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
2 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
3 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
4 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
5 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
6 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
7 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
8 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
9 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
10 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
#2. Thread
0 libsystem_kernel.dylib 0x183c65dbc __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x183d76fa0 _pthread_wqthread + 884
2 libsystem_pthread.dylib 0x183d76c20 start_wqthread + 4
#3. Thread
0 libsystem_kernel.dylib 0x183c65dbc __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x183d76fa0 _pthread_wqthread + 884
2 libsystem_pthread.dylib 0x183d76c20 start_wqthread + 4
#4. Thread
0 libsystem_kernel.dylib 0x183c65dbc __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x183d76fa0 _pthread_wqthread + 884
2 libsystem_pthread.dylib 0x183d76c20 start_wqthread + 4
#5. Thread
0 libsystem_kernel.dylib 0x183c65dbc __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x183d77134 _pthread_wqthread + 1288
2 libsystem_pthread.dylib 0x183d76c20 start_wqthread + 4
#6. com.apple.uikit.eventfetch-thread
0 libsystem_kernel.dylib 0x183c44bc4 mach_msg_trap + 8
1 libsystem_kernel.dylib 0x183c44a3c mach_msg + 72
2 CoreFoundation 0x1840f5c74 __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x1840f3840 __CFRunLoopRun + 1424
4 CoreFoundation 0x184013fb8 CFRunLoopRunSpecific + 436
5 Foundation 0x184a3d6e4 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 304
6 Foundation 0x184a5cafc -[NSRunLoop(NSRunLoop) runUntilDate:] + 96
7 UIKit 0x18e1472f4 -[UIEventFetcher threadMain] + 136
8 Foundation 0x184b3e860 __NSThread__start__ + 996
9 libsystem_pthread.dylib 0x183d7831c _pthread_body + 308
10 libsystem_pthread.dylib 0x183d781e8 _pthread_body + 310
11 libsystem_pthread.dylib 0x183d76c28 thread_start + 4
#7. Thread
0 libsystem_kernel.dylib 0x183c65dbc __workq_kernreturn + 8
1 libsystem_pthread.dylib 0x183d77134 _pthread_wqthread + 1288
2 libsystem_pthread.dylib 0x183d76c20 start_wqthread + 4
#8. Thread
0 testapp-swift 0x1046b9934 runtime.mach_semaphore_timedwait + 20
1 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
2 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
3 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
4 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
5 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
6 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
7 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
8 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
9 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
10 testapp-swift 0x10468fdd4 runtime.semasleep1 + 196
#9. Thread
0 testapp-swift 0x1046b990c runtime.mach_semaphore_wait + 12
1 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
2 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
3 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
4 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
5 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
6 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
7 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
8 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
9 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
10 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
#10. Thread
0 testapp-swift 0x1046b990c runtime.mach_semaphore_wait + 12
1 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
2 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
3 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
4 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
5 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
6 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
7 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
8 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
9 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
10 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
#11. Thread
0 testapp-swift 0x1046b990c runtime.mach_semaphore_wait + 12
1 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
2 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
3 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
4 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
5 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
6 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
7 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
8 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
9 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
10 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
#12. Thread
0 testapp-swift 0x1046b990c runtime.mach_semaphore_wait + 12
1 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
2 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
3 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
4 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
5 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
6 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
7 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
8 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
9 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
10 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
#13. Thread
0 testapp-swift 0x1046b990c runtime.mach_semaphore_wait + 12
1 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
2 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
3 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
4 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
5 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
6 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
7 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
8 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
9 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
10 testapp-swift 0x10468fd50 runtime.semasleep1 + 64
#14. com.twitter.crashlytics.ios.MachExceptionServer
0 libsystem_kernel.dylib 0x183c44bc4 mach_msg_trap + 8
1 libsystem_kernel.dylib 0x183c44a3c mach_msg + 72
2 testapp-swift 0x1046fcaa4 CLSMachExceptionServer + 100
3 libsystem_pthread.dylib 0x183d7831c _pthread_body + 308
4 libsystem_pthread.dylib 0x183d781e8 _pthread_body + 310
5 libsystem_pthread.dylib 0x183d76c28 thread_start + 4
#15. com.apple.NSURLConnectionLoader
0 libsystem_kernel.dylib 0x183c44bc4 mach_msg_trap + 8
1 libsystem_kernel.dylib 0x183c44a3c mach_msg + 72
2 CoreFoundation 0x1840f5c74 __CFRunLoopServiceMachPort + 196
3 CoreFoundation 0x1840f3840 __CFRunLoopRun + 1424
4 CoreFoundation 0x184013fb8 CFRunLoopRunSpecific + 436
5 CFNetwork 0x18477e264 +[NSURLConnection(Loader) _resourceLoadLoop:] + 404
6 Foundation 0x184b3e860 __NSThread__start__ + 996
7 libsystem_pthread.dylib 0x183d7831c _pthread_body + 308
8 libsystem_pthread.dylib 0x183d781e8 _pthread_body + 310
9 libsystem_pthread.dylib 0x183d76c28 thread_start + 4