Vision Shutdown() crash

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## Description
App crashes for some users upon starting `VisionManager`
## Stack Trace
```
Crashed: com.apple.main-thread
0 MapboxVisionNative 0x106a5c5a0 cva::Core::Shutdown() + 56
1 MapboxVisionNative 0x106a3b3a8 _hidden#1032_ + 744
2 MapboxVisionNative 0x106a2f8b4 mapbox::vision::ios::onIssueDetected() + 12260
3 MapboxVisionNative 0x106a0388c _hidden#584_ + 45532
4 MapboxVision 0x1069085d4 VisionManager.start() + 234 (VisionManager.swift:234)
5 AppName 0x104761ef8 ARNavigation.start() + 37 (ARNavigation.swift:37)
6 AppName 0x104761d54 @objc ARNavigation.viewDidLoad() + 4343749972 (:4343749972)
7 UIKitCore 0x1b656aaac -[UIViewController _sendViewDidLoadWithAppearanceProxyObjectTaggingEnabled] + 104
8 UIKitCore 0x1b656f660 -[UIViewController loadViewIfRequired] + 952
9 UIKitCore 0x1b656fa4c -[UIViewController view] + 32
10 AppName 0x1046a70cc UIViewController.present(viewController:on:below:withConstraints:) + 18 (UIViewController+Children.swift:18)
11 AppName 0x1047560f0 CameraController.loadARNavigation(with:) + 468 (Camera.swift:468)
12 AppName 0x1047559f0 closure #1 in CameraController.switchPIP(with:map:) + 393 (Camera.swift:393)
13 AppName 0x10470e79c thunk for @escaping @callee_guaranteed () -> () + 4343408540 (:4343408540)
14 libdispatch.dylib 0x1b2732ec4 _dispatch_call_block_and_release + 32
15 libdispatch.dylib 0x1b273433c _dispatch_client_callout + 20
16 libdispatch.dylib 0x1b2740600 _dispatch_main_queue_callback_4CF + 832
17 CoreFoundation 0x1b2a0f6b0 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 16
18 CoreFoundation 0x1b2a0a2c8 __CFRunLoopRun + 1708
19 CoreFoundation 0x1b2a098f4 CFRunLoopRunSpecific + 480
20 GraphicsServices 0x1bce20604 GSEventRunModal + 164
21 UIKitCore 0x1b6bdd358 UIApplicationMain + 1944
22 AppName 0x10468fab0 main + 27 (MapRouteSelection.swift:27)
23 libdyld.dylib 0x1b28852dc + 4
```

## Configuration
- Device: iPhone 11 (log from this phone)
- OS: iOS 13.5.0
- Frameworks versions (leave the ones you're using):
- MapboxVisionNativeAll ~ 0.13.1
- MapboxVision ~ 0.13.1
- MapboxVisionAR ~ 0.13.1
- MapboxVisionSafety ~ 0.13.1

Start at VisionManager.swift:234 and compare the VisionManager.start() call with the native cva::Core::Shutdown() stack frames. Reproduce the crash using an iPhone 11 on iOS 13.5 with the listed 0.13.1 frameworks; done means starting VisionManager no longer crashes for the affected configuration.

Written by the indexing model from the issue text.