[Bug] Update results in SearchHandler crashes on real iOS device

Description

When updating the SearchHandler.ItemsSource property, it works fine on an iOS simulator but crashes on a real device.

Objective-C exception thrown.  Name: NSInvalidArgumentException Reason: -[UIKit_UISearchController___Xamarin_UISearchResultsUpdating updateSearchResultsForSearchController:]: unrecognized selector sent to instance 0x2829d9940
Native stack trace:
	0   CoreFoundation                      0x00000002100a5294 <redacted> + 252
	1   libobjc.A.dylib                     0x000000020f27f9f8 objc_exception_throw + 56
	2   CoreFoundation                      0x000000020ffc1ab8 <redacted> + 0
	3   CoreFoundation                      0x00000002100aa7c0 <redacted> + 636
	4   CoreFoundation                      0x00000002100ac75c _CF_forwarding_prep_0 + 92
	5   UIKitCore                           0x000000023c8d6da0 <redacted> + 836
	6   UIKitCore                           0x000000023c8d6a28 <redacted> + 284
	7   UIKitCore                           0x000000023c8d6184 <redacted> + 32
	8   UIKitCore                           0x000000023c0f03d4 <redacted> + 152
	9   UIKitCore                           0x000000023c869040 <redacted> + 96
	10  UIKitCore                           0x000000023c3121c8 <redacted> + 80
	11  UIKitCore                           0x000000023c3124e8 <redacted> + 440
	12  UIKitCore                           0x000000023cb5c414 <redacted> + 720
	13  UIKitCore                           0x000000023cb4f394 <redacted> + 180
	14  UIKitCore                           0x000000023c0f369c <redacted> + 92
	15  UIKitCore                           0x000000023cb4f1b4 <redacted> + 28
	16  UIKitCore                           0x000000023c0f398c <redacted> + 304
	17  UIKitCore                           0x000000023c872dec <redacted> + 296
	18  UIKitCore                           0x000000023c86193c <redacted> + 352
	19  UIKitCore                           0x000000023c88e7ac <redacted> + 116
	20  CoreFoundation                      0x00000002100365f8 <redacted> + 32
	21  CoreFoundation                      0x0000000210031320 <redacted> + 412
	22  CoreFoundation                      0x000000021003189c <redacted> + 1228
	23  CoreFoundation                      0x00000002100310b0 CFRunLoopRunSpecific + 436
	24  GraphicsServices                    0x000000021223179c GSEventRunModal + 104
	25  UIKitCore                           0x000000023c867978 UIApplicationMain + 212
	26  Xaminals.iOS                        0x000000010169a7a8 Xaminals.iOS + 4286376
	27  Xaminals.iOS                        0x000000010162418c Xaminals.iOS + 3801484
	28  Xaminals.iOS                        0x000000010162414c Xaminals.iOS + 3801420
	29  Xaminals.iOS                        0x00000001012b4630 Xaminals.iOS + 198192
	30  Xaminals.iOS                        0x00000001015858d8 Xaminals.iOS + 3152088
	31  Xaminals.iOS                        0x0000000102616bd0 mono_pmip + 24712
	32  Xaminals.iOS                        0x0000000102684270 mono_pmip + 472872
	33  Xaminals.iOS                        0x000000010268952c mono_pmip + 494052
	34  Xaminals.iOS                        0x00000001025fd9d8 Xaminals.iOS + 20421080
	35  Xaminals.iOS                        0x000000010272fa2c _Z9__isctypeim + 47160
	36  Xaminals.iOS                        0x00000001012b4530 Xaminals.iOS + 197936
	37  libdyld.dylib                       0x000000020faf68e0 <redacted> + 4

Steps to Reproduce

1. Clone the Xaminals sample (https://github.com/xamarin/xamarin-forms-samples/tree/master/UserInterface/Xaminals/Xaminals)
2. Debug the iOS project in a simulator
3. Select the search bar and try typing something
4. Results appear
5. Debug the iOS project on an iPhone
6. Select the search bar
7. The app crashes with a native stack trace

Expected Behavior

Changing the value of ItemsSource should not crash the application

Actual Behavior

Changing the value of ItemsSource crashes the application

Basic Information

• Version with issue: 4.0.0.425677
• IDE: Visual Studio for Mac
• Platform Target Frameworks:
  • iOS: 12.2 (Xamarin.iOS 12.2.1.16 - Deployment Target 8.0)
• Affected Devices: iPhone 6 (iOS 12.3.1)

Reproduction Link

https://github.com/xamarin/xamarin-forms-samples/blob/master/UserInterface/Xaminals