iOS doesNotRecognizeSelector in CoreFoundation - ios

Question

I'm getting crash from our custom keyboard extension that shows doesNotRecognizeSelector in the report but the code that's crashing isn't mine... it's in Foundation/CoreFoundation. Here's the crash report...
Incident Identifier: B7818....
CrashReporter Key: 57ce8....
Hardware Model: iPhone9,2
Process: MyApp Keyboard [7390]
Path: /private/var/containers/Bundle/Application/AB6EA.....B37/MyApp.app/PlugIns/MyApp Keyboard.appex/MyApp Keyboard
Identifier: com.MyDomain.MyApp.MyApp-Keyboard
Version: 288 (3.12)
Code Type: ARM-64 (Native)
Role: Foreground
Parent Process: launchd [1]
Coalition: com.MyDomain.MyApp.MyApp-Keyboard [710]
Date/Time: 2018-03-07 16:51:29.4017 -0500
Launch Time: 2018-03-07 16:51:28.3872 -0500
OS Version: iPhone OS 11.2.6 (15D100)
Baseband Version: 3.42.00
Report Version: 104
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Triggered by Thread: 4
Last Exception Backtrace:
0 CoreFoundation 0x18146b164 __exceptionPreprocess + 124 (NSException.m:166)
1 libobjc.A.dylib 0x1806b4528 objc_exception_throw + 56 (objc-exception.mm:521)
2 CoreFoundation 0x181478628 -[NSObject(NSObject) doesNotRecognizeSelector:] + 140 (NSObject.m:322)
3 CoreFoundation 0x181470b10 ___forwarding___ + 1380 (NSForwarding.m:3220)
4 CoreFoundation 0x181355ccc _CF_forwarding_prep_0 + 92
5 Foundation 0x181df65e4 -[NSExtensionContext _willPerformHostCallback:] + 180 (NSExtensionContext.m:838)
6 Foundation 0x181df32d4 __105-[_NSExtensionContextVendor _beginRequestWithExtensionItems:listenerEndpoint:withContextUUID:completion:]_block_invoke + 780 (NSExtensionContext.m:268)
7 libdispatch.dylib 0x180deaa54 _dispatch_call_block_and_release + 24 (init.c:994)
8 libdispatch.dylib 0x180deaa14 _dispatch_client_callout + 16 (object.m:502)
9 libdispatch.dylib 0x180df496c _dispatch_queue_serial_drain$VARIANT$mp + 528 (inline_internal.h:2500)
10 libdispatch.dylib 0x180df52fc _dispatch_queue_invoke$VARIANT$mp + 340 (queue.c:5302)
11 libdispatch.dylib 0x180df5d20 _dispatch_root_queue_drain_deferred_wlh$VARIANT$mp + 404 (queue.c:5920)
12 libdispatch.dylib 0x180dfe03c _dispatch_workloop_worker_thread$VARIANT$mp + 644 (source.c:2529)
13 libsystem_pthread.dylib 0x181092f1c _pthread_wqthread + 932 (pthread.c:2207)
14 libsystem_pthread.dylib 0x181092b6c start_wqthread + 4
I can see the doesNotRecognizeSelector at line 2 and the nearest thing in the stack is NSExtensionContext _willPerformHostCallback. I looked through all the threads in the report and nothing shows anything from our code. I searched our codebase and I don't see any code where we override willPerformHostCallback or anything derived from NSExtensionContext for that matter.
Can anybody see what the deal is here?
TIA, Mike