[iOS] ReactNativePageView.m line 154 crash

## Environment

iOS
```
"react-native-pager-view": "^5.4.9",
"react-native": "0.66.1",
```

## Description

We get a number of crash reports in crashlytics about next issue:
```
ReactNativePageView.m line 154
-[ReactNativePageView setupInitialController]
```

```
Fatal Exception: NSRangeException
*** -[__NSArrayM objectAtIndexedSubscript:]: index 18446744073709551615 beyond bounds [0 .. 0]
Fatal Exception: NSRangeException
0 CoreFoundation 0x9270c __exceptionPreprocess
1 libobjc.A.dylib 0x14f04 objc_exception_throw
2 CoreFoundation 0x18c984 -[__NSCFString characterAtIndex:].cold.1
3 CoreFoundation 0x354c8 __NSDictionaryMutablePlaceholder
4 APPNAME 0x3c513c -[ReactNativePageView setupInitialController] + 154 (ReactNativePageView.m:154)
5 APPNAME 0x3c4884 -[ReactNativePageView didMoveToWindow] + 92 (ReactNativePageView.m:92)
6 UIKitCore 0x29f760 -[UIView(Internal) _didMoveFromWindow:toWindow:]
7 UIKitCore 0x29f244 -[UIView(Internal) _didMoveFromWindow:toWindow:]
8 UIKitCore 0x29f244 -[UIView(Internal) _didMoveFromWindow:toWindow:]
9 UIKitCore 0x29f244 -[UIView(Internal) _didMoveFromWindow:toWindow:]
10 UIKitCore 0x29f244 -[UIView(Internal) _didMoveFromWindow:toWindow:]
11 UIKitCore 0x1cbf00 __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke
12 UIKitCore 0x257adc -[UIView(Hierarchy) _postMovedFromSuperview:]
13 UIKitCore 0x17a20c -[UIView(Internal) _addSubview:positioned:relativeTo:]
14 UIKitCore 0x25f6c4 -[UITransitionView transition:fromView:toView:removeFromView:]
15 UIKitCore 0x2bf838 -[UIViewControllerBuiltinTransitionViewAnimator animateTransition:]
16 UIKitCore 0x48a170 ___UIViewControllerTransitioningRunCustomTransition_block_invoke_2
17 UIKitCore 0x2c88f0 +[UIKeyboardSceneDelegate _pinInputViewsForKeyboardSceneDelegate:onBehalfOfResponder:duringBlock:]
18 UIKitCore 0x33b35c ___UIViewControllerTransitioningRunCustomTransition_block_invoke.641
19 UIKitCore 0x3c1d58 +[UIView(Animation) _setAlongsideAnimations:toRunByEndOfBlock:]
20 UIKitCore 0x265698 _UIViewControllerTransitioningRunCustomTransition
21 UIKitCore 0x88fd20 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke.401
22 UIKitCore 0x30c4cc -[_UIAfterCACommitBlock run]
23 UIKitCore 0x227b8c -[_UIAfterCACommitQueue flush]
24 UIKitCore 0x156518 _runAfterCACommitDeferredBlocks
25 UIKitCore 0x156be4 _cleanUpAfterCAFlushAndRunDeferredBlocks
26 UIKitCore 0x156db0 _afterCACommitHandler
27 CoreFoundation 0x3e21c __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
28 CoreFoundation 0xf454 __CFRunLoopDoObservers
29 CoreFoundation 0xa9dc __CFRunLoopRun
30 CoreFoundation 0x1dc30 CFRunLoopRunSpecific
31 GraphicsServices 0x1988 GSEventRunModal
32 UIKitCore 0x4e5c50 -[UIApplication _run]
33 UIKitCore 0x27f3d0 UIApplicationMain
34 APPNAME 0x7044 main + 14 (main.m:14)
35 ??? 0x1058ec3d0 (Missing)
```
Have anybody experienced something similar and can help identifying the problem of the crash?

Beginne bei ReactNativePageView.m in Zeile 154 und verfolge setupInitialController von didMoveToWindow aus. Reproduziere die NSRangeException mit react-native-pager-view 5.4.9 und React Native 0.66.1 und grenze anschließend den fehlschlagenden Zustand des initialen Controllers ein. Als erledigt gilt die Aufgabe, wenn die Ursache des Absturzes reproduzierbar ist und entweder eine verifizierte Behebung oder klare Reproduktionsdetails vorliegen.

Vom Indexierungsmodell aus dem Issue-Text verfasst.