App crash using Sharknado tabs with Xamarin Shell

[stackunderflows]

Platform (please complete the following information):

• OS: Both
• Device: Pixel 2 XL emulator, iPhone Xr emulator
• Sdk vervion: iOS 12.2, Android 8.1
• Xamarin.Forms: 4.0

Describe the bug
I created a new Xamarin Forms Shell app. In the shell, I specified a flyout menu. I defaulted the first page to just have a label on it. Another page in the flyout has Sharknado tabs at the top of it.

To Reproduce
Steps to reproduce the behavior:

1. Launch the app. You're brought to a page that just has a label on it because it is specified first in the shell.
2. Click on the hamburger menu and navigate to the page that has tabs on it.
3. Click on the hamburger menu again and navigate to a page that doesn't have tabs on it.
4. App crashes.

Exceptions (if applicable)

Unhandled Exception:
System.ArgumentNullException: Value cannot be null.
Parameter name: key
  at System.Collections.Generic.Dictionary`2[TKey,TValue].FindEntry (TKey key) [0x00008] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/external/corefx/src/Common/src/CoreLib/System/Collections/Generic/Dictionary.cs:380 
  at System.Collections.Generic.Dictionary`2[TKey,TValue].ContainsKey (TKey key) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.8.0.2/src/Xamarin.iOS/external/corefx/src/Common/src/CoreLib/System/Collections/Generic/Dictionary.cs:286 
  at Sharpnado.Presentation.Forms.iOS.Effects.TapGestureCollector.Delete (UIKit.UIView view, System.Action action) [0x00001] in /Users/mrampanelli/Projects/Sharpnado.Presentation.Forms/Sharpnado.Presentation.Forms.iOS/Effects/TapGestureCollector.cs:49 
  at Sharpnado.Presentation.Forms.iOS.Effects.iOSViewStyleEffect.OnDetached () [0x0004b] in /Users/mrampanelli/Projects/Sharpnado.Presentation.Forms/Sharpnado.Presentation.Forms.iOS/Effects/ViewStyleEffect .cs:67 
  at Xamarin.Forms.Effect.SendDetached () [0x00009] in D:\a\1\s\Xamarin.Forms.Core\Effect.cs:62 
  at Xamarin.Forms.PlatformEffect`2[TContainer,TControl].SendDetached () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\PlatformEffect.cs:23 
  at Xamarin.Forms.RoutingEffect.SendDetached () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\RoutingEffect.cs:34 
...

I downloaded the Sharknado code and figured out the problem. In 2 places, the view variable is coming through as null. In TapGestureRecognizerCollector Delete method and LongTapGestureCollector Delete method. Adding a null check fixes the problem.

[roubachof]

Well done!
I think I will make a new release next week (I have some vacation time :)

[roubachof]

fixed in v1.2.0