shutdown crash: engine does not seem to be running

```
std::__1::system_error: mutex lock failed: Invalid argument

0 unknown file unknown method

Thread 0
0 libsystem_kernel.dylib ___psynch_cvwait
1 libsystem_pthread.dylib __pthread_cond_wait$VARIANT$armv81
2 Lyft absl::synchronization_internal::Waiter::Wait(absl::synchronization_internal::KernelTimeout) (Lyft)
3 Lyft AbslInternalPerThreadSemWait (Lyft)
4 Lyft absl::Mutex::Block(absl::base_internal::PerThreadSynch*) (Lyft)
5 Lyft absl::Mutex::LockSlowLoop(absl::SynchWaitParams*, int) (Lyft)
6 Lyft absl::Mutex::LockSlowWithDeadline(absl::MuHowS const*, absl::Condition const*, absl::synchronization_internal::KernelTimeout, int) (Lyft)
7 Lyft absl::Mutex::LockSlow(absl::MuHowS const*, absl::Condition const*, int) (Lyft)
8 Lyft absl::Mutex::Lock() (Lyft)
9 Lyft Envoy::Engine::~Engine() (Lyft)
10 Lyft std::__1::shared_ptr >::~shared_ptr() (Lyft)
11 libsystem_c.dylib ___cxa_finalize_ranges
12 libsystem_c.dylib _exit
13 UIKitCore -[UIApplication _terminateWithStatus:]
14 UIKitCore -[_UISceneLifecycleMultiplexer _evalTransitionToSettings:fromSettings:forceExit:withTransitionStore:]
15 UIKitCore -[_UISceneLifecycleMultiplexer forceExitWithTransitionContext:scene:]
16 UIKitCore -[UIApplication workspaceShouldExit:withTransitionContext:]
17 FrontBoardServices -[FBSUIApplicationWorkspaceShim workspaceShouldExit:withTransitionContext:]
18 FrontBoardServices ___83-[FBSWorkspaceScenesClient willTerminateWithTransitionContext:withAcknowledgement:]_block_invoke_2
19 FrontBoardServices -[FBSWorkspace _calloutQueue_executeCalloutFromSource:withBlock:]
20 FrontBoardServices ___83-[FBSWorkspaceScenesClient willTerminateWithTransitionContext:withAcknowledgement:]_block_invoke
21 libdispatch.dylib __dispatch_client_callout
22 libdispatch.dylib __dispatch_block_invoke_direct$VARIANT$armv81
23 FrontBoardServices __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__
24 FrontBoardServices -[FBSSerialQueue _queue_performNextIfPossible]
25 FrontBoardServices -[FBSSerialQueue _performNextFromRunLoopSource]
26 CoreFoundation ___CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__
27 CoreFoundation ___CFRunLoopDoSource0
28 CoreFoundation ___CFRunLoopDoSources0
29 CoreFoundation ___CFRunLoopRun
30 CoreFoundation _CFRunLoopRunSpecific
31 GraphicsServices _GSEventRunModal
32 UIKitCore _UIApplicationMain
33 Lyft main (Lyft)
34 libdyld.dylib _start

Thread 1
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 2
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 3
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 4
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 5
0 libsystem_kernel.dylib _mach_msg_trap
1 libsystem_kernel.dylib _mach_msg
2 CoreFoundation ___CFRunLoopServiceMachPort
3 CoreFoundation ___CFRunLoopRun
4 CoreFoundation _CFRunLoopRunSpecific
5 Foundation -[NSRunLoop(NSRunLoop) runMode:beforeDate:]
6 Foundation -[NSRunLoop(NSRunLoop) runUntilDate:]
7 UIKitCore -[UIEventFetcher threadMain]
8 Foundation ___NSThread__start__
9 libsystem_pthread.dylib __pthread_start

Thread 6
0 libsystem_kernel.dylib _mach_msg_trap
1 libsystem_kernel.dylib _mach_msg
2 libsystem_kernel.dylib _thread_suspend
3 Lyft ksmachexc_i_handleExceptions (Lyft)
4 libsystem_pthread.dylib __pthread_start

Thread 7
0 libsystem_kernel.dylib _mach_msg_trap
1 libsystem_kernel.dylib _mach_msg
2 Lyft ksmachexc_i_handleExceptions (Lyft)
3 libsystem_pthread.dylib __pthread_start

Thread 8
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 9
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 10
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 11
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 12
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 13
0 libsystem_kernel.dylib _mach_msg_trap
1 libsystem_kernel.dylib _mach_msg
2 CoreFoundation ___CFRunLoopServiceMachPort
3 CoreFoundation ___CFRunLoopRun
4 CoreFoundation _CFRunLoopRunSpecific
5 CFNetwork 0x1836d6c40 (-0x2d268000 + 7257451584)
6 Foundation ___NSThread__start__
7 libsystem_pthread.dylib __pthread_start

Thread 14
0 libsystem_kernel.dylib _mach_msg_trap
1 libsystem_kernel.dylib _mach_msg
2 CoreFoundation ___CFRunLoopServiceMachPort
3 CoreFoundation ___CFRunLoopRun
4 CoreFoundation _CFRunLoopRunSpecific
5 CoreFoundation _CFRunLoopRun
6 CoreMotion _CLClientCreateIso6709Notation
7 libsystem_pthread.dylib __pthread_start

Thread 15
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 16
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 17
0 libsystem_kernel.dylib _mach_msg_trap
1 libsystem_kernel.dylib _mach_msg
2 CoreFoundation ___CFRunLoopServiceMachPort
3 CoreFoundation ___CFRunLoopRun
4 CoreFoundation _CFRunLoopRunSpecific
5 Foundation -[NSRunLoop(NSRunLoop) runMode:beforeDate:]
6 Lyft -[GMSx_GTMSimpleWorkerThread main] (Lyft)
7 Foundation ___NSThread__start__
8 libsystem_pthread.dylib __pthread_start

Thread 18
0 libsystem_kernel.dylib _select$DARWIN_EXTSN
1 CoreFoundation ___CFSocketManager
2 libsystem_pthread.dylib __pthread_start

Thread 19
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 20
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 21
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 22
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 23

Thread 24
0 libsystem_kernel.dylib _read
1 Foundation __NSReadFromFileDescriptorWithProgress
2 Foundation __NSReadBytesFromFileWithExtendedAttributes
3 Foundation -[NSData(NSData) initWithContentsOfFile:options:maxLength:error:]
4 Lyft AnalyticsPublishing.Archiver.next(Swift.Int) throws -> AnalyticsPublishing.Archiver.Group (Lyft)
5 Lyft AnalyticsPublishing.Publisher.(uploadNext in _A0B54219BEFE611FFEAC579B46F660D4)() -> () (Lyft)
6 Lyft closure #1 () -> () in closure #2 (Swift.Result<(), Swift.Error>) -> () in AnalyticsPublishing.Publisher.(uploadNext in _A0B54219BEFE611FFEAC579B46F660D4)() -> () (Lyft)
7 Lyft reabstraction thunk helper from @escaping @callee_guaranteed () -> () to @escaping @callee_unowned @convention(block) () -> () (Lyft)
8 Foundation ___NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__
9 Foundation -[NSBlockOperation main]
10 Foundation ___NSOPERATION_IS_INVOKING_MAIN__
11 Foundation -[NSOperation start]
12 Foundation ___NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__
13 Foundation ___NSOQSchedule_f
14 libdispatch.dylib __dispatch_block_async_invoke2
15 libdispatch.dylib __dispatch_client_callout
16 libdispatch.dylib __dispatch_continuation_pop$VARIANT$armv81
17 libdispatch.dylib __dispatch_async_redirect_invoke
18 libdispatch.dylib __dispatch_root_queue_drain
19 libdispatch.dylib __dispatch_worker_thread2
20 libsystem_pthread.dylib __pthread_wqthread

Thread 25
0 libsystem_kernel.dylib ___workq_kernreturn
1 libsystem_pthread.dylib __pthread_wqthread

Thread 26
```

Start with the shutdown stack trace, especially Envoy::Engine::~Engine(), and compare it with the iOS termination path shown in the report. Reproduce the shutdown sequence if possible and determine what change prevents the mutex-lock crash without introducing a new shutdown failure.

Written by the indexing model from the issue text.